Question

i am trying to prototype the String Object to have a replaceWith Function that make me able to replace directly without using regular expression

String.prototype.replaceWith = function(f, t) {
    var regExp = new RegExp("[" + f + "]", "g");
    return this.replace(regExp, t);
};

when i tested my code in this string {{Hello}} for example i found that replacing double curly braces is a problem

Test

'{{Hello}}'.replaceWith('{{','<<').replaceWith('}}','>>');

Result is

 "<<<<Hello>>>>"

when it should be

"<<Hello>>"

what is wrong with my script ??

thanks for your help

Answer 1

[{{] is the exact same as [{] which is the same as just { in regex. The square brackets indicate a character class which matches one of any characters within that class. You should just change:

"[" + f + "]"

To:

f

So you have:

String.prototype.replaceWith = function(f, t) {
    var regExp = new RegExp(f, "g");
    return this.replace(regExp, t);
};

Which as Marlin pointed out has the same functionality as String.prototype.replace except you don’t need to add the g modifier, and in my mind '{{Hello}}'.replace(/{{/g, '<<'); is more concise and understandable to other coders than '{{Hello}}'.replaceWith('{{', '<<');.