Date.prototype.toISOString
Returns a string in simplified extended ISO format (ISO 8601), which is always 24 or 27 characters long
Syntax
date.toISOString()Return Value
A string representing the date in ISO 8601 format
Examples
const date = new Date('2024-06-15T14:30:00Z');
console.log(date.toISOString()); // '2024-06-15T14:30:00.000Z'const now = new Date();
const isoDate = now.toISOString().split('T')[0];
console.log(isoDate); // '2024-06-15'const dates = [
new Date('2024-01-01'),
new Date('2023-06-15'),
];
const sorted = dates.sort((a, b) =>
a.toISOString().localeCompare(b.toISOString())
);Understanding Date.prototype.toISOString
The Date.prototype.toISOString method in JavaScript returns a string in simplified extended ISO format (ISO 8601), which is always 24 or 27 characters long. It belongs to the Date object and is one of the most widely used methods for working with date values in modern JavaScript and TypeScript applications.
The method signature is date.toISOString(). When called, it returns a string representing the date in iso 8601 format. Understanding when and how to use toISOString() helps you write more expressive, readable code.
Common use cases for Date.prototype.toISOString include data transformation, input validation, API response processing, and building reusable utility functions. It works well alongside related methods like date-tojson, date-tolocalestring, date-tolocaledatestring, enabling you to chain operations together for complex data manipulation pipelines.
Browser support for Date.prototype.toISOString is excellent across all modern browsers including Chrome, Firefox, Safari, and Edge. It is also fully supported in Node.js and Deno. For older environments, transpilation with Babel or a polyfill may be needed.
Browser Compatibility
Supported in all modern browsers (Chrome, Firefox, Safari, Edge) and Node.js. Part of the ECMAScript standard.
Related Methods
Date.prototype.toJSONReturns a string representation of the Date object for use by JSON.stringify, which calls toISOString under the hood
Date.prototype.toLocaleStringReturns a string with a language-sensitive representation of this date, including both date and time
Date.prototype.toLocaleDateStringReturns a string with a language-sensitive representation of the date portion of this date
More Date Methods
Other methods in the Date object
Related Tools
More Date Methods
Explore JavaScript Methods
Browse our complete reference of 410 JavaScript methods with syntax, examples, and explanations.