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The toISOString() method returns a string in simplified extended ISO format (ISO 8601), which is always 24 or 27 characters long (YYYY-MM-DDTHH:mm:ss.sssZ or ±YYYYYY-MM-DDTHH:mm:ss.sssZ, respectively). The timezone is always zero UTC offset, as denoted by the suffix "Z".



Return value

A string representing the given date in the ISO 8601 format according to universal time.


Using toISOString()

var today = new Date('05 October 2011 14:48 UTC');

console.log(today.toISOString()); // Returns 2011-10-05T14:48:00.000Z

The above example uses parsing of a non–standard string value that may not be correctly parsed in non–Mozilla browsers.


This method was standardized in ECMA-262 5th edition. Engines which have not been updated to support this method can work around the absence of this method using the following shim:

if (!Date.prototype.toISOString) {
  (function() {

    function pad(number) {
      if (number < 10) {
        return '0' + number;
      return number;

    Date.prototype.toISOString = function() {
      return this.getUTCFullYear() +
        '-' + pad(this.getUTCMonth() + 1) +
        '-' + pad(this.getUTCDate()) +
        'T' + pad(this.getUTCHours()) +
        ':' + pad(this.getUTCMinutes()) +
        ':' + pad(this.getUTCSeconds()) +
        '.' + (this.getUTCMilliseconds() / 1000).toFixed(3).slice(2, 5) +



Specification Status Comment
ECMAScript 5.1 (ECMA-262)
The definition of 'Date.prototype.toISOString' in that specification.
Standard Initial definition. Implemented in JavaScript 1.8.
ECMAScript 2015 (6th Edition, ECMA-262)
The definition of 'Date.prototype.toISOString' in that specification.
ECMAScript 2017 Draft (ECMA-262)
The definition of 'Date.prototype.toISOString' in that specification.

Browser compatibility

Feature Chrome Firefox (Gecko) Internet Explorer Opera Safari
Basic support (Yes) (Yes) 9 (Yes) (Yes)
Feature Android Chrome for Android Firefox Mobile (Gecko) IE Mobile Opera Mobile Safari Mobile
Basic support (Yes) (Yes) (Yes) (Yes) (Yes) (Yes)

See also

Document Tags and Contributors

 Last updated by: eduardoboucas,