JavaScript JSON parse() metoden

定义和用法

JSON.parse() 方法解析字符串并返回 JavaScript 对象。

该字符串必须以 JSON 格式编写。

JSON.parse() 方法可以选择使用函数来转换结果。

实例

例子 1

解析一个字符串（以 JSON 格式编写）并返回一个 JavaScript 对象：

var obj = JSON.parse('{"firstName":"Bill", "lastName":"Gates"}');

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Example 2

How to use the reviver function:

/* Replace the "city" value with uppercase: */
var text = '{ "name":"Bill", "age":"19", "city":"Seattle"}';
var obj = JSON.parse(text, function (key, value) {
  if (key == "city") {
    return value.toUpperCase();
  } else {
    return value;
  }
});
document.getElementById("demo").innerHTML = obj.name + ", " + obj.city;

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Example 3

Parse JSON received from the server:

var xmlhttp = new XMLHttpRequest();
xmlhttp.onreadystatechange = function() {
  if (this.readyState == 4 && this.status == 200) {
    var myObj = JSON.parse(this.responseText);
    document.getElementById("demo").innerHTML = myObj.name;
  }
};
xmlhttp.open("GET", "json_demo.txt", true);
xmlhttp.send();

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See json_demo.txt

Syntax

JSON.parse(string, function)

Parameter value

Parameter Description
string Required. A string written in JSON format.
reviver function

Optional. A function used to transform the result. Call this function for each item. Any nested objects are transformed before the parent object.

If this function returns a valid value, replace the item value with the converted value.

If this function returns undefined, delete this item.

Technical details

Return value: JSON object, or number.
JavaScript version: ECMAScript 5

Browser supports

Tal i tabellen angiver den første browserversion, der fuldt ud understøtter denne metode.

Metoder Chrome IE Firefox Safari Opera
parse() 4.0 8.0 3.5 4.0 11.5

Relaterede sider

JSON tutorial:JSON introduktion