How to properly use trim

[durangod]

This is what i have, is this correct?

if the client enters spaces after the input i want to trim it

//in this example the input is blue_ _ _   (_=spaces)

var inp = document.subregfrm.squest.value; 
var answ = inp.trim();

//answ should = blue   (no spaces)

Thanks

[Philip M]

The trim() function is native to PHP (and other languages) but the Javascript inbuilt function String.trim() is implemented only in the most modern browsers. Prefer:-

var inp = "   abc   "
var answ = inp.replace(/^\s+|\s+$/g,"");  // the g switch is essential!!

or if you prefer something re-usable:-

function trim(str) {
return str.replace(/^\s+|\s+$/g,"");
}

Quizmaster: Since 1920 a statue of which former US President has resided in Parliament Square?
Contestant: Ronald Reagan

[rnd me]

for performance, readability, and consistency, one should always use the native syntax.

Its actually been several years now that String.prototoype.trim() has been bundled with browsers.

if you need backwards-compatibility (aka graceful degradation) use a ployfill to make sure the String method is the same as it is in all current versions of all major browsers:

in the case of trim(), we can do it 100% backwards compatible, so there's no reason to have to balance an extra pair of parens when the proto is so handy:

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

if you already hard-coded trim(str) into your code, you can speed up your flow by re-binding the native:

var trim=eval.call.bind("".trim);

//example usage:
trim( "  hello   ");

[Philip M]

String.prototoype.trim() is not implemented in IE<9. I see nothing wrong with the regex I suggested.

[rnd me]

Originally Posted by Philip M

String.prototoype.trim() is not implemented in IE<9. I see nothing wrong with the regex I suggested.

right, which is why i used your regex and posted a polyfill version allowing you to use String.prototype.trim() in IE 5-8...

if you want to bench the two, you'll find the native version, which runs in C, executes dozens of times faster than a user regexp.

but above performance, its about coding style. why write custom code using a proprietary syntax when you can easily use the native syntax, even in 3-version old IE using the code i posted.

protos are easier to code because they are an after-thought, added to the right of a string expression, whereas functions have to wrap the expression. its much quicker to type [SHIFT]+[9][0] than two separate shift presses and some arrow keys, and protos separate content from presentation with a dot.