How to Pass Variables into JavaScript Regular Expressions for String Replacement?

Passing Variables into Regular Expressions for String Replacement in JavaScript

When attempting to create a String.replaceAll() method using regular expressions, one may encounter difficulties in passing variables into the regex. To overcome this challenge, it is essential to understand the correct syntax.

Creating a Dynamic Regular Expression

Instead of using the conventional /sREGEXs/g syntax, create a new RegExp object as follows:

// variable == 'REGEX'
let re = new RegExp(String.raw`\s${variable}\s`, "g");

Using the Regex Object

Once the regex object is constructed, you can use it to replace the desired string:

"mystring1".replace(re, "newstring");

Note for Older Browsers or Node

For older browsers or Node.js versions, you can use the following syntax:

// variable == 'REGEX'
var re = new RegExp("\s" + variable + "\s", "g");
"mystring1".replace(re, "newstring");

By following these instructions, you can effectively pass variables into regular expressions and perform string replacements in JavaScript.

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