THE WORLD'S LARGEST WEB DEVELOPER SITE

JavaScript RegExp ?= Quantifier

❮ JavaScript RegExp Object

Example

Do a global search for "is" followed by " all":

var str = "Is this all there is";
var patt1 = /is(?= all)/g;

The marked text below shows where the expression gets a match:

Is this all there is
Try it Yourself »

Definition and Usage

The ?=n quantifier matches any string that is followed by a specific string n.

Tip: Use the ?!n quantifier to match any string that is NOT followed by a specific string n.


Browser Support

Expression
?= Yes Yes Yes Yes Yes

Syntax

new RegExp("regexp(?=n)")

or

/regexp(?=n)/

Syntax with modifiers

new RegExp("regexp(?=n)","g")

or simply:

/\regexp(?=n)/g

❮ JavaScript RegExp Object