How to Dynamically Inject Variables into Regular Expressions in JavaScript?

Putting Variables Inside Regular Expressions: A Revised Solution

In software development, incorporating dynamic values into regular expressions can be a challenge. This article explores an effective solution to this issue, offering a revised answer to the commonly asked question: "How to put a variable inside a regular expression in JavaScript?"

The original approach attempted to insert a variable into a regular expression using string concatenation. However, this method is not suitable as it treats the variable as a literal string rather than a dynamic value.

The solution presented here involves creating a new regular expression using the RegExp constructor and a template string. This technique allows you to embed variables into the expression dynamically.

const regex = new RegExp(`ReGeX${testVar}ReGeX`);
...
string.replace(regex, "replacement");

Security Considerations

When utilizing user-supplied input in regular expressions, it is crucial to escape the variable to prevent malicious input from disrupting your code.

ES6 Update

With the advent of ES6, the recommended approach has been updated to use template strings, which offer enhanced readability and conciseness.

var regex = new RegExp(`ReGeX${testVar}ReGeX`);
...
string.replace(regex, "replacement");

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