Date.prototype.toISOString()

Baseline Widely available

This feature is well established and works across many devices and browser versions. It’s been available across browsers since July 2015.

The toISOString() method of Date instances returns a string representing this date in the date time string format, a simplified format based on 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 UTC, as denoted by the suffix Z.

Try it

const event = new Date("05 October 2011 14:48 UTC");
console.log(event.toString());
// Expected output: "Wed Oct 05 2011 16:48:00 GMT+0200 (CEST)"
// Note: your timezone may vary

console.log(event.toISOString());
// Expected output: "2011-10-05T14:48:00.000Z"

Syntax

toISOString()

Parameters

None.

Return value

A string representing the given date in the date time string format according to universal time. It's the same format as the one required to be recognized by Date.parse().

Exceptions

RangeError

Thrown if the date is invalid or if it corresponds to a year that cannot be represented in the date string format.

Examples

Using toISOString()

js
const d = new Date(0);

console.log(d.toISOString()); // "1970-01-01T00:00:00.000Z"

Specifications

Specification

ECMAScript® 2027 Language Specification
# sec-date.prototype.toisostring

Browser compatibility

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This page was last modified on Jul 10, 2025 by MDN contributors.

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Standard built-in objects
Date
Constructor
1. Date()
Static methods
Instance methods
Inheritance
Object/Function
Static methods
Static properties
Instance methods
Instance properties
1. __proto__
2. constructor