JavaScript RegExp ?= Modifier
Complete RegExp Object Reference
Definition and Usage
When the ?= modifier is set the regular expression gets a match if the string to search for is followed by a specific string.
Syntax
new RegExp("regexp(?=ahead)")
OR
/regexp(?=ahead)/
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Parameter |
Description |
regexp |
Required. The rest of the regular expression to use |
ahead |
What the string must be followed by to get a match |
Example
In the following code we will do a search for "is" if it is ahead of " all":
var str = "Is this all there is";
var patt1 = new RegExp("is(?= all)");
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The marked text below shows where the RegExp gets a match:
Try-It-Yourself Demos
?=
How to use the "?=" modifier to search for a string followed by another string
using a string object.
?=
How to use the "?=" modifier to search for a string followed by another string
using a regular expression object.
Complete RegExp Object Reference
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