JavaScript RegExp ?= Quantifier
Example
A search for "is" followed by " all":
let text = "Is this all there is";
let pattern = /is(?= all)/g;
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
/(?=n)/ is an ECMAScript1 (ES1) feature.
ES1 (JavaScript 1997) is fully supported in all browsers:
| Chrome | Edge | Firefox | Safari | Opera | IE |
| Yes | 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
