replace all occurrences of a character in a javascript string

Question

I need to replace all occurrences of these 2 characters "_1" in a string with "_2", but Regex does not accept to put a variable there.

var current_registration_number = 1;
html = html.replace(/\_{current_registration_number}/g, '_'+next_registration_number);

Somebody help me get through this problem?

Answer 1

You don’t need to use regex you can use .split()/.join() which separates the string by this character and then joins back together by inserting the new character as a union of these parts:

html = html.split('_' + current_registration_number ).join('_' + next_registration_number);

To use regex you have to use the constructor new RegExp();:

var regex = new RegExp('\\_' + current_registration_number, 'g');
html = html.replace(regex, '_' + next_registration_number);

Notice you have to use it twice \\ because that string you pass to the constructor "escapes" in the conversion.