How to rewrite this JS to support trim()

Question

How can I rewrite the following to do the same thing but to also support trim() for IE.

var isAnonymous = settings.requester_name == null || settings.requester_name.trim() == "";

Answer 1

Try:

var isAnonymous = !settings.requester_name || !settings.requester_name.trim();

And you can use this polyfill:

if (!String.prototype.trim) {
  String.prototype.trim = function () {
    return this.replace(/^[\s\xA0]+|[\s\xA0]+$/g, '');
  };
}

Answer 2

You can use as below, if trim() is not supported

function myTrim(x) {
   return x.replace(/^\s+|\s+$/gm,'');
}

function myFunction() {
   var str = myTrim("        Hello World!        ");
   alert(str);
}

Demo

Answer 3

In Javascript an empty string is a falsy value, so is null or undefined, given that the following should work

var isAnonymous = !settings.requester_name || !settings.requester_name.trim()

The second part of the expression converts the empty string into a boolean, which evaluates false if empty.

What version of IE are you using? Trim has been supported for a while...

If you are writing for older than ie9 you can add a polyfill for trim

if (!String.prototype.trim) {
   String.prototype.trim = function () {
     return this.replace(/^[\s\xA0]+|[\s\xA0]+$/g, '');
   };
}    

FFR: Mozilla developer network is a great source for Javascript app docs, and they include polyfill implementations you can use for old browser support.

Heres the docs for trim (the polyfill may look familiar) https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/String/Trim