Question
I would like to create a String.replaceAll() method in JavaScript and I'm
thinking that using a regex would be most terse way to do it. However, I can't
figure out how to pass a variable in to a regex. I can do this already which
will replace all the instances of "B" with "A".
"ABABAB".replace(/B/g, "A");
But I want to do something like this:
String.prototype.replaceAll = function(replaceThis, withThis) {
this.replace(/replaceThis/g, withThis);
};
But obviously this will only replace the text "replaceThis"...so how do I
pass this variable in to my regex string?
Answer
Instead of using the /regex\d/g syntax, you can construct a new
[RegExp](https://developer.mozilla.org/en-
US/docs/JavaScript/Guide/Regular_Expressions) object:
var replace = "regex\\d";
var re = new RegExp(replace,"g");
You can dynamically create regex objects this way. Then you will do:
"mystring1".replace(re, "newstring");
