Question

I’m trying to create a simple prototype in JavaScript that removes a character from a string (like Python’s strip). This may well exist already in JavaScript, but I can’t find it and this is more of an exercise for me than a replacement for something that already exists.

function strip(chars) {
    this.replace(chars,"");
}

String.prototype.strip=strip;

var wrong = "Hellow";

alert(wrong.strip("w"));

When I run this code, the alert says “Undefined”. My suspicion is the this. in the function but not sure. I’ve also made a fiddle here: http://jsfiddle.net/jdb1991/rapxM/

Thanks

Answer 1

You have to specify return, so that the result of the operation is returned:

function strip(chars) {
   return this.replace(chars,"");
}

Working demo: http://jsfiddle.net/rapxM/1/

Notice that your code does not remove all characters, it does only remove the first occurrence. If you want to remove all characters, use:

function strip(chars) {
   return this.split(chars).join('');
}

• .split splits the string in smaller pieces, based on the given argument (returned value: array).
• .join() is an array method, which concatenates the array (returned value: string)