JavaScript: Internet Explorer 8 and the trim() function

In fact, trim() is only supported since IE9 and even in this version, the support is not given in each mode.

One workaround is to just define your own trim function:

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

This function checks in the if-statement whether there is a function "trim" defined or available for the string type. If not, an own function "trim" will be defined consisting of a regular expression. This RegEx cares about removing the white space from both sides of the string.
2014-05-21 at 16:49

If you are already using jQuery on your website, you can also just use the trim() function from jQuery:

var s = ' abc ';

s = $.trim(s);

alert(s);  // 'abc'

As you can see in the example, you can simply use this function via $.trim().
2014-05-22 at 17:12