JSON.parse Function (JavaScript)

Deserializes JavaScript Object Notation (JSON) text to produce a JavaScript value.

JSON.parse(text [, reviver])


Required. Valid JSON text.


Optional. A function that filters and transforms the results. The deserialized object is traversed recursively, and the reviver function is called for each member of the object in post-order (every object is revived after all its members have been revived). For each member, the following occurs:

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

  • If reviver returns what it received, the structure is not modified.

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

The reviver argument is often used to transform JSON representation of International Organization for Standardization (ISO) date strings into Coordinated Universal Time (UTC) format Date objects.

A JavaScript value—an object or array.



JavaScript parser errors

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.

  • Make sure that the text argument was serialized by a JSON-compliant implementation, such as, JSON.stringify.

This example uses JSON.parse to deserialize JSON text into the contact object.

var jsontext = '{"firstname":"Jesper","surname":"Aaberg","phone":["555-0100","555-0120"]}';
var contact = JSON.parse(jsontext);
var fullname = contact.surname + ", " + contact.firstname;
// The value of fullname is "Aaberg, Jesper"

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);
var string = dates.birthdate.toUTCString();
// The value of string is "Thu, 25 Dec 2008 12:00:00 UTC"

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;

Supported in the following document modes: Internet Explorer 8 standards, Internet Explorer 9 standards. See Version Information.

Not supported in the following document modes: Quirks, Internet Explorer 6 standards, Internet Explorer 7 standards.

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