Using a Javascript variable within a regular expression

Question

Using a Javascript variable within a regular expression

Looking for guidance on how to effectively use a variable in a regular expression with JavaScript.

I attempted this approach:

var regex = new RegExp('/^' + name + '/');
var result = cookie.name.match(regex);

However, when I debug the 'regex' variable, I get:

/\/^foobar\//

Just to clarify, I am trying to match a cookie named foobar_xxxxxxxx

Why does such a seemingly simple task turn out to be so complex? I have come across many other queries about this issue, but none of the solutions seem to work in my scenario.

javascript regex

Answer 1

Answer №1

No slashes are required when writing regular expressions using the RegExp function.

Answer 2

No slashes are required when writing regular expressions using the RegExp function.

Answer 3

Answer №2

After removing the slashes, I found success. When using new RegExp, it automatically adds the / so there's no need to include it separately. You can refer to this for more information:

https://developer.mozilla.org/en-US/docs/Web/JavaScript/Guide/Regular_Expressions

let name = 'foobar'
var regex = new RegExp('^' + name);
var result = 'foobar_xxxxxxxx'.match(regex);

Answer 4

After removing the slashes, I found success. When using new RegExp, it automatically adds the / so there's no need to include it separately. You can refer to this for more information:

https://developer.mozilla.org/en-US/docs/Web/JavaScript/Guide/Regular_Expressions

let name = 'foobar'
var regex = new RegExp('^' + name);
var result = 'foobar_xxxxxxxx'.match(regex);

Using a Javascript variable within a regular expression

Answer №1

Answer №2

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