JSON syntax
A subset of JavaScript object representation syntax.
- Data in name/value pair
- Data separated by commas
- Braces save objects
- Save array in brackets
JSON value type
- Number (integral or floating point number)
- String (in double quotes)
- Logical value (true or false)
- Array (in brackets)
- Object (in braces)
- null
JSON object
{ "name":"boonya", "alexa":10000, "site":null }
JSON objects are written in braces ({}).
An object can contain multiple key/value pairs.
The key must be a string, and the value can be a legal JSON data type (string, number, object, array, boolean, or null).
Key and value are split using colon (:).
Each key/value pair is split using comma (,).
JSON array
[ "Google", "Tencent", "Taobao" ]
or
[ {"name":"Google"},{"name": "Tencent"}, {"name":"Taobao"} ]
or
{
"data":[ {"name":"Google"},{"name": "Tencent"}, {"name":"Taobao"} ]
}
JSON arrays are written in brackets.
The array value in JSON must be a legal JSON data type (string, number, object, array, boolean, or null).
In JavaScript, the array value can be the above JSON data type, or it can be a JavaScript expression, including functions, dates, and undefined.
JSON string data to object: ()
JSON is usually used to exchange data with the server.
It is usually a string when receiving server data.
We can use the () method to convert data into JavaScript objects.
(text[, reviver])
Parameter description:
- text: Required, a valid JSON string.
- reviver: Optional, a function that converts the result, which will call this function for each member of the object.
Object to string JSON data: ()
JSON is usually used to exchange data with the server.
It is usually a string when sending data to the server.
We can use the () method to convert JavaScript objects into strings.
(value[, replacer[, space]])
Parameter description:
- value:
Required, the JavaScript value to be converted (usually an object or an array).
- replacer:
Optional. Function or array used to convert results.
If replacer is a function, the function is called and the key and value of each member are passed in. Use the return value instead of the original value. If this function returns undefined, members are excluded. The key of the root object is an empty string: "".
If replacer is an array, only members with key values in that array are converted. The conversion order of members is the same as the order of keys in the array. When the value parameter is also an array, the replacer array is ignored.
- space:
Optionally, text adds indentation, space, and line breaks. If space is a number, the return value text indents the specified number of spaces at each level, and if space is greater than 10, the text indents 10 spaces. space can also use non-numeric, such as:\t.
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