Detailed explanation of the use, intercept and splicing of the most practical string (string) type of js

var a = 'The farthest distance in the world is not the ends of the world';

1. Get the position through characters or get the character through positions:

//Specify the return character((1));
(str[1]);
//Return character encoding at the specified position((1));
 
//Return to the string position(("o"));//Return -1 if not present(("o"));

The execution results in the browser are as follows:

If there is a variable now:

var a = 'The farthest distance in the world is not the ends of the world';

var b = 'Farest distance';

Now if you want to dynamically get the string before variable b and the string after variable, you can do this

1. Use slice to get the previous string;

2. Get the length of variable b, add the length of b after the initial position of b, and intercept the length of a from the tail of b (of course, when the length can be omitted!);

2. Splicing strings:

There are generally two types:

a. Use "+" directly;

function

3. Cutting method

((3,7));//Start, end (there is a start, an end)((3,7));//Start, end (there is a start, an end)((3,7));//Start, length (with start, no end, length) 
((-3,-2));//The first negative value is added to the length, and the second negative value is added to the length((3,-1));//The first negative value is converted to 0, the second negative value is converted to 0, if the start is greater than the end, then the adjustment is made((-3,-1));//The first negative value is added to the length, and the second negative value is converted to 0

Here is an example:

var type can be dir/file

if (type !== 'dir' && ('.') !== -1) {//file
 basename=(0,('.'));
 extension=(('.'));
} else {//dir
 basename=name;
 extension=false;
}


//Chinese

4. Remove the spaces before and after

var strValue = " hello world! ";
var trimedStrValue = ();
(strValue);
(trimedStrValue);

5. Case conversion method

var strLowUp = "HELLO world!";
(());
(());
(strLowUp);

6. Methods related to patterns, the caller is a string, and the parameters are a pattern (regular object or regular expression or string)

1. Matching method is essentially the same as the exec() method that calls RegExp (the caller is a regular expression or a regular object, and the parameters are strings)
//Return the array object, the first item is the matching string, and the other items are the matching strings to the capture group
//Return object has both index and input properties. Index is the index matching the string, and input is the string str that matches the string.

2. Query/Search Method
//The return value is the index of the matching character. If it is not queried, it will return -1

The search() method is used to retrieve the specified substring in a string, or to retrieve the substring that matches a regular expression.

3. Replace method, two parameters, replace parameter one with parameter two, parameter one is a string or regular expression, parameter two is a string or function

a. //Regular

b. String

c. Function

//If the second parameter is a function//The parameters received by the function are: the matched substring,  The first capture group matches the substring、
  The substring matched by the second capture group...、Index of pattern matching、Original string
var repStr = (/at/g,function(match,index,input){
(match);//at
(index);//
(input);//cat,bat,sat,fat
return "an";
});
 
(repStr);//can,ban,san,fan

4. Segmentation method, divide the string into multiple substrings according to the specified separator.

 
//The return value is an array that stores multiple substringsvar str = "red,blue,green,yellow";
var strArray = (",");
var strArray = (/[^\,]+/);//Match all characters that are not comma as delimiters(strArray);//["red", "blue", "green", "yellow"]
 
//The second parameter is used to control the length of the arrayvar strArray = (",",2);
(strArray);//["red", "blue", "green", "yellow"]

7. Comparison method, the return values ​​are 1(>0), 0, -1(<0)

var strValue = "yellow";
(("brick"));//>0
(("yellow"));//0
(("zoo"));//<0

The above is the detailed explanation and integration of js string using interception and splicing introduced by the editor. I hope it will be helpful to everyone. If you have any questions, please leave me a message and the editor will reply to everyone in time. Thank you very much for your support for my website!