The multiline property indicates whether or not the "m" flag is used with the regular expression. multiline is a read-only property of an individual regular expression instance.

Property attributes of RegExp.prototype.multiline
Writable no
Enumerable no
Configurable yes


The value of multiline is a Boolean and is true if the "m" flag was used; otherwise, false. The "m" flag indicates that a multiline input string should be treated as multiple lines. For example, if "m" is used, "^" and "$" change from matching at only the start or end of the entire string to the start or end of any line within the string.

You cannot change this property directly.


Using multiline

var regex = new RegExp('foo', 'm');

console.log(regex.multiline); // true


Specification Status Comment
ECMAScript 3rd Edition (ECMA-262) Standard Initial definition. Implemented in JavaScript 1.2. JavaScript 1.5: multiline is a property of a RegExp instance, not the RegExp object.
ECMAScript 5.1 (ECMA-262)
The definition of 'RegExp.prototype.multiline' in that specification.
ECMAScript 2015 (6th Edition, ECMA-262)
The definition of 'RegExp.prototype.multiline' in that specification.
Standard multiline is now a prototype accessor property rather than an instance's own data property.
ECMAScript 2017 Draft (ECMA-262)
The definition of 'RegExp.prototype.multiline' in that specification.

Browser compatibility

Feature Chrome Firefox (Gecko) Internet Explorer Opera Safari
Basic support (Yes) (Yes) (Yes) (Yes) (Yes)
Prototype accessor property ? 38 (38) ? ? ?
Feature Android Chrome for Android Firefox Mobile (Gecko) IE Mobile Opera Mobile Safari Mobile
Basic support (Yes) (Yes) (Yes) (Yes) (Yes) (Yes)
Prototype accessor property ? ? 38.0 (38) ? ? ?

Compatibility notes

  • Prior to SpiderMonkey 48 (Firefox 48 / Thunderbird 48 / SeaMonkey 2.45), a non-standard, global RegExp.multiline property existed in addition to this RegExp.prototype.multiline property. It is removed in newer versions (see bug 1219757). Use the property described on this page or the m flag instead.

See also


© 2016 Mozilla Contributors
Licensed under the Creative Commons Attribution-ShareAlike License v2.5 or later.

JavaScript Property Prototype Reference RegExp Regular Expressions