Value attributes
These properties are just simple values, and they do not have their own properties and methods.
Infinity
Global property Infinity is a numeric value that represents infinity.
NaN
The value of the global attribute NaN indicates that it is not a number (Not-A-Number).
undefined
The global attribute undefined indicates the original value undefined. It is a JavaScript primitive data type.
null
The value null specifically refers to the object's value not set. It is one of the basic types of JavaScript.
Function Properties
Global functions can be called directly, and there is no need to specify the object to which they belong during the call. After the execution is completed, the result will be returned directly to the caller.
eval(str)
The eval() function will execute the passed string as JavaScript code.
PS: eval can cause safety and performance problems, seeAvoid using eval when unnecessary。
isFinite(arg)
Determine whether the value passed in (non-number type will be converted to number type) is a finite value.
isNaN()
Determine whether the value passed in (non-number type will be converted to number type) is NaN.
PS: Use () instead to replace it is more semantic.
parseFloat(str)
The parseFloat() function parse a string parameter and returns a floating point number.
PS: If a character other than the exponent (e or E) in the parsing process is encountered during the parsing process, it will ignore the character and all subsequent characters and return the currently parsed floating point number. At the same time, the whitespace at the first position of the parameter string will be ignored.
If the first character cannot be parsed, it will return directly to NaN.
parseInt(str, radix);
The parseInt() function parse a string parameter and returns an integer with a specified cardinality (the basis of a mathematical system).
PS: radix an integer between 2 and 36, representing the cardinality of the above string (default is 10).
encodeURI(URI)
Functions encode a Uniform Resource Identifier (URI) by replacing each instance of a specific character with one, two, three or four escape sequences (the character's UTF-8 encoding is only four escape sequences) consists of two "proxy" characters).
PS: encodeURI All characters except letters, numbers,;,,,/,?,:, @, &,=, +, $, -, _, .,!, ~, *, ', (,), #,.
decodeURI(encodeURI)
The decodeURI() function decodes a unified resource identifier (URI) or similar routine created previously by the encodeURI.
encodeURIComponent(str)
encodeURIComponent() is a method of encoding components of a unified resource identifier (URI).
PS: encodeURIComponent escapes all characters except letters, numbers, (,), ., !, ~, *, ', - and _.
In order to avoid unpredictable requests from the server, you need to escape any content entered by the user as part of the URI by encodeURIComponent.
decodeURIComponent(encodedURI)
The decodeURIComponent() method is used to decode part of the Uniform Resource Identifier (URI) encoded by the encodeURIComponent method or other similar methods.
The difference between encodeURI and encodeURIComponent and usage scenarios
The difference is that the encoded characters are different.
encodeURI is used to encode the entire URI and encodeURIComponent is the main query part (when you need to encode the parameters in the URL).
Simple and clear distinction between escape, encodeURI and encodeURIComponent
Function
A global Function object does not have its own properties and methods, but because it is also a function itself, it will also inherit some properties and methods from above through the prototype chain.
Prototype properties
length
Definition: Specifies the number of formal parameters of a function (determines how many parameters that must be passed in) are different from the number of actual parameters (determines the actual number of parameters passed when the function is called).
constructor
Definition: Returns a reference to the Object constructor that created the instance object.
Prototype method
(thisArg, [argsArray])
Definition: Call a function with a specified value of this and the parameters provided as an array (or an array-like object).
Parameters: thisArg is the pointer of this when the func function is executed, and argsArray is the class array parameter array.
Returns: The result of calling a function with the specified value and parameters.
(thisArg, arg1, arg2, …)
Definition: Call a function with a specified value of this and the parameters provided separately (list of parameters).
Parameters: thisArg is the pointer of this when the func function is executed, arg1, arg2, ... is the specified parameter list.
Return: The return value is the return value of the method you call. If the method does not return value, it will return undefined.
Use: 1. Use the call method to call the parent constructor (in a child constructor, you can implement inheritance by calling the call method of the parent constructor)
2. Call anonymous function using call method 3. Call the function using call method and specify the 'this' of the context
Use examples
(thisArg[, arg1[, arg2[, …]]])
Definition: Call a function with a specified value of this and the parameters provided as an array (or an array-like object).
Parameters: thisArg is when the binding function is called, this parameter will be pointed as this when the original function runs. arg1, arg2... when the binding function is called, these parameters will be placed before the actual parameter and passed to the bound method.
Returns: a copy of the original function modified from the specified this value and initialization parameters (returns a function).
Application: 1. Create a binding function (explicitly bind this) 2. Partial function (make a function have preset initial parameters).
Use examples
()
Definition: Returns a string representing the source code of the current function.
Parameters: null.
Return: A string representing the function source code.
Number
JavaScript's Number object is an encapsulated object that allows you to process numeric values.
Number(), if the parameter cannot be converted to a number, returns NaN.
property
The minimum interval between two representable numbers, the error is considered reasonable in this range when performing calculations.
Number.MAX_SAFE_INTEGER
The largest secure integer in JavaScript (2^53 - 1).
Number.MIN_SAFE_INTEGER
The smallest safe integer in JavaScript (-(2^53 - 1)).
Number.MAX_VALUE
The maximum positive number that can be represented. The smallest negative number is -MAX_VALUE.
Number.MIN_VALUE
The smallest positive number that can be represented is the positive number closest to 0 (it won't actually become 0). The largest negative number is -MIN_VALUE.
Not A Number.
Number.NEGATIVE_INFINITY
A special negative infinity value that returns when overflowed.
Number.POSITIVE_INFINITY
A special positive infinity value returns a modified value when overflowed.
method
None of the following methods will happen to convert String into Number.
(value)
Definition: Determines whether the passed value is NaN and its type is Number. It is used instead of the original global isNaN().
Parameters: To be detected whether it is the value of NaN.
Returns: A Boolean value indicating whether the given value is NaN.
PS: This method is different from the global isNaN() and does not convert strings to numbers.
(value)
Definition: Used to detect whether the passed parameter is a finite number.
Parameter: value to be detected with finite value.
Return: A Boolean value indicates whether the given value is a finite number.
PS: Compared with the global isFinite() function, this method does not force a non-numeric parameter to a numeric value.
(value)
Definition: used to determine whether the given parameter is an integer.
Parameter: value to determine whether this parameter is an integer.
Return: determines whether the given value is the Boolean value of an integer.
(testValue)
Definition: Used to determine whether the passed parameter value is a "safe integer".
Parameters: The parameters that testValue needs to be detected.
Return: A boolean value indicates whether the given value is a safe integer.
(string)
Definition: A string can be parsed into a floating point number.
Parameters: string parsed string.
Return: the corresponding floating point number.
PS: Same as the global function parseFloat().
(string[, radix])
Definition: A string number can be parsed into an integer based on the given binary number.
Parameters: string to parse the value, radix an integer between 2 and 36 (the basis of a mathematical system), representing the cardinality of the above string.
Example method
The following methods are returned as strings.
([fractionDigits])
Definition: Returns the numeric string representation in exponential representation.
Parameters: fractionDigits An integer that specifies how many digits there are after the decimal point.
Return: A string representing the Number object in the form of power (scientific notation).
(digits)
Definition: Use fixed-point notation to format a number.
Parameters: digits the number of numbers after the decimal point.
Returns: The string form of the fixed-point representation of the given value.
(precision)
Definition: Returns the string representation of the numeric object with the specified precision.
Parameters: precision An integer used to specify a valid number.
Returns: A string representation of a numeric object represented by fixed-point notation or exponential notation.
([locales [, options]])
Definition: Returns the representation string of this number in a specific locale.
Parameters: locales are the numbering system to be used locally, options are the following properties (localeMatcher, style, currency, etc. but have certain compatibility)
Return: Returns a locale representation string.
PS: Usually used to format into some form of currency.
([radix])
Definition: Returns the string representation of the specified Number object.
Parameters: radix specifies the cardinality (from 2 to 36) to be used for the conversion of a number to string.
Return: The converted string.
()
Definition: Returns a raw value wrapped by a Number object.
Returns: A number representing the original value of the specified Number object.
String
Static method
(num1, …, numN)
Definition: Returns a string created with the specified sequence of Unicode values.
(num1[, …[, numN]])
Definition: Returns a string created with the specified sequence of code points, but this method does not recognize 32-bit UTF-16 characters (Unicode number greater than 0xFFFF).
(callSite, …substitutions) || templateString
is used to obtain the original literal value of a template string.
Instance properties
length
Returns: The length of the string.
N
Returns: Nth string, but cannot be changed.
Example method
(index)
Definition: Returns the character of the specified index from a string, with the default parameter 0.
(index)
Definition: Returns the number of the UTF-16 code unit value of the character at the given index; if the index is out of range, returns NaN.
(index)
Definition: Returns a non-negative integer with Unicode encoded point value.
(string2, string3[, …, stringN])
Definition: Merge one or more strings with the original string to form a new string and return.
(searchString[, index])
Definition: Determine whether a string is contained in another string, and returns true or false according to the situation.
(searchString [, index])
Definition: used to determine whether the current string begins with another given substring, and returns true or false according to the judgment result.
(searchString [, index]);
Definition: Determine whether the current string ends with another given substring, and returns true or false according to the judgment result.
(searchValue[, index])
Definition: The index of the specified value that appears for the first time, start searching in Index, otherwise return -1.
(searchValue[, index])
Definition: Returns the last location of the specified value in the string in which the method is called, and -1 if not found.
(compareString[, locales[, options]])
Definition: The localeCompare() method returns a number indicating whether a reference string is before or after the sort order or the same as the given string.
(regexp);
Definition: When a string matches a regular expression, the match() method retrieves the match.
([form]);
Definition: The current string will be normalized in a specified Unicode regular form.
(targetLength [, padString])
Definition: A string will be filled before the current string (repeat if necessary), and returns a string that reaches the specified length after filling.
(targetLength [, padString])
Definition: A string will be filled after the current string (repeat if necessary), and returns a string that reaches the specified length after filling.
(count);
Definition: Returns a new string containing a copy of the specified number of strings concatenated together.
PS: The parameters start from zero.
(regexp|substr, newSubStr|function)
Definition: Returns a new string after replacing some or all matching patterns by the replacement value.
If the first parameter is regexp and the second parameter is function, the parameter description of the function
Parameter 1: String that matches the pattern.
Parameter 2 –: The subexpression is a matching substring (that is, capture grouping).
Countdown parameter 2: Declare the location where the match appears in the string.
Countdown parameter 1: Make the matching sting itself.
(regexp)
Definition: A search match between a row regular expression and a String object.
Return: If the match is successful, search() returns the index of the first match of the regular expression in the string. Otherwise, return -1.
(beginSlice[, endSlice])
Definition: Extract part of a string and return a new string.
Parameters: beginSlice starts extracting characters from the original string from this index (based on 0 as the cardinality). If the value is negative, it will be regarded as sourceLength + beginSlice, where sourceLength is the length of the string.
endSlice ends extracting the string at this index (0 as the cardinality), and can also be a negative number.
([separator[, limit]])
Definition: Use the specified separator string to split a String object into a string array to separate the string into substrings to determine the location of each split.
(start[, length])
Definition: Returns characters in a string starting from the specified position to the specified number of characters.
PS: start >= or length <= 0 returns an empty string; start < 0 is converted to start + .
(indexStart[, indexEnd])
Definition: Returns a subset of a string between the start index and the end index, or a subset from the start index until the end of the string.
PS: Some special circumstances.
If indexStart is equal to indexEnd, substring returns an empty string.
If indexEnd is omitted, substring extracts characters until the end of the string.
If any parameter is less than 0 or is NaN, it is considered 0.
If any parameter is greater than , it is considered as .
If indexStart is greater than indexEnd, the execution effect of substring is like two parameters being replaced.
()
Definition: Converts the string value that calls this method to lowercase and returns the new string.
()
Definition: Converts the string value that calls this method to uppercase and returns the new string.
()
Definition: Returns the value of the call string converted to lowercase based on any locale-specific case map.
PS: In most cases, the result produced by this method is the same as the result of calling toLowerCase() (except Türkiye, etc.).
()
Definition: Use locale-specific case mapping rules to convert the input string into uppercase form and return the result string.
()
Definition: Returns the string form of the specified object.
()
Definition: A whitespace character will be removed from both ends of a string and a new string will be returned.
PS: () and () are not standard methods.
string[]
Returns a new Iterator object that iterates over the code points of the string and returns the string value of each code point.
PS: The following built-in types have the default iterator behaviors Array, String, Set, Map, etc., but Object does not.
Array
Static method
In ES2015, the Class syntax allows us to create new subclasses (such as SubArray) for built-in types (such as Array) and custom classes. These subclasses will also inherit the static methods of the parent class, such as (), which will return an instance of the subclass SubArray instead of an instance of Array after calling this method.
(arrayLike[, mapFn[, thisArg]])
Definition: Create a new array instance from an array-like or iterable object.
parameter:
arrayLike wants to convert a pseudo-array object or iterable object into an array.
mapFn (optional parameter) If this parameter is specified, each element in the new array executes the callback function.
thisArg (optional parameter) Optional parameter, this object when executing the callback function mapFn.
Return: a new array.
PS: (obj, mapFn, thisArg) is equivalent to (obj).map(mapFn, thisArg). The practice before ES6: (arrayLike).
(obj)
Definition: Determines whether the passed value is an Array.
Return: boolean.
PS: What was done before ES6 (arg) === ‘[object Array]’.
(element0[, element1[, …[, elementN]]])
Definition: Create a new array instance with variable number of parameters regardless of the number or type of parameters.
Parameters: Any parameters will be returned to the elements in the array in order.
Returns: an array composed of parameter lists.
The difference between PS:() and the Array constructor is that it handles integer parameters: (7) creates an array with a single element 7, while Array(7) creates an array with 7 undefined elements.
Example methods and properties
Return: Read and write the length of the array.
Modifier method (change the original array)
(target[, start[, end]])
Definition: Shallow copy part of an array to another location in the same array and return it without modifying its size.
parameter:
target 0 is the index of the substrate, and the sequence is copied to this position. If it is a negative number, target will start to calculate from the end. If target is greater than or equal to , no copy will occur. If target is after start, the copied sequence will be modified to conform to .
start 0 is the index of the base, and start copying the starting position of the element. If it is a negative number, start will start from the end. If start is ignored, copyWithin will be copied from 0.
end 0 is the index of the base, and the end position of the start copying element. copyWithin will be copied to this location, but does not include elements in the end location. If it is a negative number, end will be calculated from the end. If end is ignored, copyWithin will be copied to .
Return value: Operate the original array.
(value[, start[, end]])
Definition: Fill all elements in an array from the starting index to the end index with a fixed value.
parameter:
value is used to fill the value of the array element.
start start index, default is 0.
end end index, default is (excluding).
Return: Modified array.
(element1, …, elementN)
Definition: Add one or more elements to the end of the array and return the length of the new array.
parameter:
elementN The element added to the end of the array.
Returns: The length of the array after the operation.
()
Definition: Removes the last element from the array and returns the value of that element. This method changes the length of the array.
Returns: Elements removed from the array (returned undefined when the array is empty).
()
Definition: Reverse the positions of elements in the array.
Return: Inverts the position of the element in the array and returns the reference to the array.
(compareFunction)
Definition: The array can be sorted according to the specified method.
compareFunction optional. Used to specify functions arranged in some order. If omitted, elements are sorted by Unicode sites of the individual characters of the converted string.
Return: Returns the sorted array. The original array has been replaced by the sorted array.
()
Definition: Removes the first element from the array and returns the value of that element. This method changes the length of the array.
Returns: Elements removed from the array; return undefined if the array is empty.
(element1, …, elementN)
Definition: Add one or more elements to the beginning of the array and return the length of the new array.
Parameters: element1, …, elementN element to be added to the element at the beginning of the array.
Return: When an object calls the method, it returns its length attribute value.
(start, [deleteCount], [item1], [item2], …)
Definition: Change the contents of an array by deleting existing elements and/or adding new elements.
parameter:
start The location where the modification begins.
deleteCount removes the number of elements of the array.
item1, item2… are the added elements.
Returns: an array of deleted elements. If only one element is deleted, an array containing only one element is returned. If no elements are deleted, an empty array is returned.
Access method (array without direct operation principle)
old_array.concat(value1[, value2[, …[, valueN]]])
Definition: Used to merge two or more arrays. This method does not change the existing array, but returns a new array.
Parameters: valueN Concatenate arrays and/or values into a new array.
Return: New array.
(searchElement, [fromIndex])
Definition: used to determine whether an array contains a specified value. According to the situation, if included, it will return true, otherwise it will return false.
parameter:
searchElement The value of the element that needs to be found.
fromIndex starts searching for searchElement from this index.
Return: boolean.
([separator])
Definition: Concatenate all elements of an array (or an array object of a class) into a string and return this string.
parameter:
searchElement The value of the element that needs to be found.
fromIndex starts searching for searchElement from this index.
Return: string.
([begin], [end])
Definition: Returns a shallow copy of a portion of an array selected from the start to the end (excluding the end) to a new array object.
Return: A new array containing the extracted elements.
(searchElement[, fromIndex = 0])
Definition: Returns the first index where a given element can be found in the array, and if it does not exist, returns -1.
Return: The index position of the first found element in the array; if not found, return -1.
(searchElement[, fromIndex = - 1])
Definition: Returns the first index where a given element can be found in the array, and if it does not exist, returns -1.
Return: The index of the last element in the array, if not found, returns -1.
()
Definition: Returns a string representing the specified array and its elements.
Returns: Comma-separated string.
Iteration method
(callback(currentValue, index, array){ //do something}, this)
Definition: Executes the provided function once on each element of the array.
Return: undefined.
PS: There is no way to abort or break out of the forEach loop. If you need to break out, please use a loop instead.
Deleted (using delete methods, etc.) or uninitialized items will be skipped (but those with values of undefined, null will not be skipped).
(callback(currentValue, index, array){ //do something}, this)
Definition: Create a new array, and the result is the result returned after each element in the array calls a provided function.
Return: A new array, each element is the result of the callback function.
()
Definition: Returns a new Array iterator that contains the keys for each index in the array.
Return: A new Array iterator object.
()
Definition: Returns a new Array Iterator object that contains the values of each index of the array.
Return: A new Array iterator object.
()
Definition: Returns a new Array Iterator object that contains key/value pairs for each index in the array.
Return: A new Array iterator object.
(callback[, thisArg])
Definition: Tests whether all elements of the array pass the test of the specified function.
Return: boolean.
(callback[, thisArg])
Definition: Testing whether certain elements in the array are passed through tests that are implemented by the provided function.
Return: boolean.
(callback[, thisArg])
Definition: Creates a new array containing all elements of the test implemented by the provided function.
Return: New array.
(callback[, thisArg])
Definition: Returns the index of the first element in the array that satisfies the provided test function. Otherwise, return -1.
Return: When an element passes the test of callback, it returns the index of a value in the array, otherwise -1 is returned.
(callback[, thisArg])
Definition: Returns the value of the first element in the array that satisfies the provided test function. Otherwise, undefined is returned.
Return: When an element passes the callback test, it returns a value in the array, otherwise it returns undefined.
(callback[, initialValue])
Definition: Apply a function to each element in the accumulator and array (from left to right) and reduce it to a single value.
parameter:
callback executes a function for each value in the array, containing four parameters:
accumulato The return value of the accumulatizer accumulative callback; it is the accumulated value returned when the callback was last called, or initialValue (as shown below).
currentValue The element being processed in the array.
currentIndex Optional The index of the current element being processed in the array. If initialValue is provided, the index number is 0, otherwise the index is 1.
array optional The array that calls reduce.
initialValue can be optionally used as the value of the first parameter to callback. If no initial value is provided, the first element in the array will be used. Calling reduce on an empty array without initial values will report an error.
Returns: The result of the accumulated processing of the function.
(callback[, initialValue])
Definition: Accept a function as an accumulator and each value of the array (right to left) reduces it to a single value.
arr
Definition: The default is an array and the iterator is not mentioned. The initial values of the @@iterator attribute and the values() attribute are both the same function object.
Returns: The iterator method of the array, which is the same as the values() return by default.
(depth)
Definition: Recursively joins all subarrays to the specified depth and returns a new array.
Parameters: depth Optionally specify the structure depth in the nested array, the default value is 1.
Returns: A new array that joins subarrays.
(function callback(currentValue[, index[, array]]) { // Return the element of the new array}[, thisArg])
Definition: First map each element using a mapping function, and then compress the result into a new array. It is almost the same as map and flatten with depth value 1, but flatMap is usually slightly more efficient in merging into one method.
Return: A new array where each element is the result of the callback function and the structure depth value is 1.
Proxy && Reflect
Proxy is a constructor (intercepting access to an object), Reflect (the API provided by the operation object).
Reflect It corresponds to the Proxy object method one by one, which allows the Proxy object to easily call the corresponding Reflect method to complete the default behavior and serve as the basis for modifying the behavior.
Proxy
Proxy is used to modify the default behavior of certain operations, which is equivalent to making modifications at the language level, so it belongs to a kind of "meta programming", that is, programming a programming language.
Proxy can be understood as setting up a layer of "intercept" before the target object. All external accesses to the object must first pass this layer, so it provides a mechanism to filter and rewrite external access.
Proxymethod：targetParameters represent the target object to be intercepted，handlerParameters are also objects，Used to customize interception behavior
var proxy = new Proxy(target, handler);
var person = {
name: "Zhang San"
};
var proxy = new Proxy(person, {
get: function(target, property) {
if (property in target) {
return target[property];
} else {
throw new ReferenceError("Property \"" + property + "\" does not exist.");
}
}
});
// "Zhang San" // Throw an error
Detailed explanation of Proxy usage
Reflect
Put some methods that obviously belong to the language (for example) on the Reflect object. At this stage, some methods are deployed on both Object and Reflect objects, and new methods in the future will only be deployed on Reflect objects. In other words, you can get the internal methods of the language from the Reflect object.
// The following method description: target is the target object, name is a certain property, and receiver is the function's this pointer
(target, thisArg, args)
The method is equivalent to (func, thisArg, args), and is used to bind this object and execute a given function.
(target, args)
Methods are equivalent to new target(…args), which provides a method that calls constructors without using new.
(target, name, receiver)
The method finds and returns the name attribute of the target object, and if there is no such attribute, it returns undefined.
(target, name, value, receiver)
Method sets the name attribute of the target object equals value.
(target, name, desc)
Methods are basically equivalent to defining attributes for objects. In the future, the latter will be gradually abolished, please use it instead from now on.
(target, name)
The method is equivalent to delete obj[name], used to delete the attributes of the object.
(target, name)
The method corresponds to the in operator in name in obj.
(target)
Methods are used to return all properties of an object, which are basically equivalent to sum with it.
(target)
The method corresponds to a Boolean value, indicating whether the current object is extensible.
(target)
Corresponding method, used to make an object not extensible. It returns a Boolean value indicating whether the operation is successful.
(target, name)
It is basically equivalent to the description object used to obtain the specified attribute, which will replace the latter in the future.
(target)
Methods are used to read objectsprotoattribute, corresponding to (obj).
(target, prototype)
Methods are used to set objectsprotoProperties, return the first parameter object, corresponding to (obj, newProto).
Event
The Event interface represents any event that occurs in the DOM; some are user-generated (such as mouse or keyboard events), while others are generated by the API (such as events indicating that the animation has completed running, the video has been paused, etc.). There are many types of events，Some of them use other interfaces based on the primary event interface。 The event itself contains properties and methods common to all events。
property
bubbles (read-only)
Definition: The boolean value used to indicate whether the event is bubbling in the DOM.
cancelBubble (discarded)
Definition: Get or set whether the current event wants to be cancelled (used () instead).
cancelable (read-only)
Definition: Indicates whether this event can cancel the default behavior (block the default behavior()).
composed (read-only)
Definition: Indicates whether the event can be passed to a general DOM by Shadow DOM.
currentTarget (read-only)
Definition: Reference to the object currently registered event, this value will change during delivery.
deepPath
Definition: Returns an Array array composed of all nodes passing through the event bubble process.
defaultPrevented (read-only)
Definition: Returns whether () has been called to prevent the default behavior.
eventPhase (read-only)
Definition: Returns the stage in which the event stream is in.
returnValue (Abandoned)
Definition: Get or set whether the default action of the event has been blocked.
target (read-only)
Definition: Returns a reference to the object that triggers the event (ie's srcElement).
timeStamp (read-only)
Definition: timestamp at event creation, millisecond level.
type (read-only)
Definition: Returns a string (case-insensitive) that represents the event type of the event object.
isTrusted (read-only)
Definition: Indicates whether the event was initiated by the browser (when the user clicks on the instance) or by a script (using the creation method of the event, for example).
Difference between target and currentTarget
Returns the element that triggers the event
Returns the element of the bound event
The difference between target and currentTarget attributes in event object
method
(“UIEvents”)
Create a new event (Event), and then you must call your own init method for initialization.
(type, bubbles, cancelable)
Definition: The () method can be used to initialize an event instance created by () and before it is triggered ().
()
Definition: If this event does not require explicit processing, then it does not do its default actions (because the default is to be done).
()
Definition: Blocks further propagation of the current event in the capture and bubble phase (only blocks the current listener).
()
Definition: Blocks other listeners that call the same event.