How to use a variable in Regular Expression pattern in JavaScript
In this article, we’ll show you how to use a variable in a Regular Expression pattern in JavaScript.
Checkout more articles on JavaScript
Here, we will refer to this article to understand the use case. In this article, we used the /is/g to replace the string. But now suppose if we have is string in the variable then we will see how to use the variable in Regular Expression.
For building a regex pattern from a dynamic string, we can use the JavaScript RegExp object.
1 2 3 4 5 6 7 8 9 | function handleReplaceAll() { var replaceStr = 'is'; var sentence = 'This is test example and it Is easy to learn.'; var re = new RegExp(replaceStr, 'g'); var output = sentence.replace(re, '-'); // Output: Th- - test example and it Is easy to learn. document.getElementById("demo").innerHTML = output; } |
Now if you want to replace the case insensitive string then you have to use gi flag. Checkout the below example.
1 2 3 4 5 6 7 8 9 | function handleReplaceAllCI() { var replaceStr = 'is'; var sentence = 'This is test example and it Is easy to learn.'; var re = new RegExp(replaceStr, 'gi'); var output = sentence.replace(re, '-'); // Output: Th- - test example and it - easy to learn. document.getElementById("demo").innerHTML = output; } |
That’s it for today.
Thank you for reading. Happy Coding..!! 🙂
