JSON.parse Function (JavaScript)

Converts a JavaScript Object Notation (JSON) string into an object.

JSON.parse(text [, reviver])

text

Required. A valid JSON string.

reviver

Optional. A function that transforms the results. This function is called for each member of the object. If a member contains nested objects, the nested objects are transformed before the parent object. For each member, the following occurs:

  • If reviver returns a valid value, the member value is replaced with the transformed value.

  • If reviver returns the same value it received, the member value is not modified.

  • If reviver returns null or undefined, the member is deleted.

An object or array.

If this function causes a JavaScript parser error (such as "SCRIPT1014: Invalid character"), the input text does not comply with JSON syntax. To correct the error, do one of the following:

  • Modify the text argument to comply with JSON syntax. For more information, see the BNF syntax notation of JSON objects.

    For example, if the response is in JSONP format instead of pure JSON, try this code on the response object:

    var fixedResponse = response.responseText.replace(/\\'/g, "'");
    var jsonObj = JSON.parse(fixedResponse);
    
  • Make sure that the text argument was serialized by a JSON-compliant implementation such as JSON.stringify.

  • Run the text argument in a JSON validator such as JSLint to help identify syntax errors.

The following example uses JSON.parse to convert a JSON string to an object.

var jsontext = '{"firstname":"Jesper","surname":"Aaberg","phone":["555-0100","555-0120"]}';
var contact = JSON.parse(jsontext);
document.write(contact.surname + ", " + contact.firstname);

// Output: Aaberg, Jesper

The following example converts an array to a JSON string by using JSON.stringify, and then converts the string back to an array by using JSON.parse.

var arr = ["a", "b", "c"];
var str = JSON.stringify(arr);
document.write(str);
document.write ("<br/>");

var newArr = JSON.parse(str);

while (newArr.length > 0) {
    document.write(newArr.pop() + "<br/>");
}


// Output:
// ["a","b","c"]
// c
// b
// a

The reviver function is often used to transform JSON representation of International Organization for Standardization (ISO) date strings into Coordinated Universal Time (UTC) format Date objects. This example uses JSON.parse to deserialize an ISO-formatted date string. The dateReviver function returns Date objects for members that are formatted like ISO date strings.

var jsontext = '{ "hiredate": "2008-01-01T12:00:00Z", "birthdate": "2008-12-25T12:00:00Z" }';
var dates = JSON.parse(jsontext, dateReviver);
document.write(dates.birthdate.toUTCString());

function dateReviver(key, value) {
    var a;
    if (typeof value === 'string') {
        a = /^(\d{4})-(\d{2})-(\d{2})T(\d{2}):(\d{2}):(\d{2}(?:\.\d*)?)Z$/.exec(value);
        if (a) {
            return new Date(Date.UTC(+a[1], +a[2] - 1, +a[3], +a[4],
                            +a[5], +a[6]));
        }
    }
    return value;
};

// Output:
// Thu, 25 Dec 2008 12:00:00 UTC

Supported in the following document modes: Internet Explorer 8 standards, Internet Explorer 9 standards, Internet Explorer 10 standards, Internet Explorer 11 standards. Also supported in Store apps (Windows 8 and Windows Phone 8.1). See Version Information. Not supported in the following document modes: Quirks, Internet Explorer 6 standards, Internet Explorer 7 standards.

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