Trim spaces from start and end of string

Question

Note: As of 2015, all major browsers (including IE>=9) support String.prototype.trim(). This means that for most use cases simply doing str.trim() is the best way of achieving what the question asks.

---

Steven Levithan analyzed many different implementation of trim in Javascript in terms of performance.

His recommendation is:

function trim1 (str) {
    return str.replace(/^\s\s*/, '').replace(/\s\s*$/, '');
}

for "general-purpose implementation which is fast cross-browser", and

function trim11 (str) {
    str = str.replace(/^\s+/, '');
    for (var i = str.length - 1; i >= 0; i--) {
        if (/\S/.test(str.charAt(i))) {
            str = str.substring(0, i + 1);
            break;
        }
    }
    return str;
}

"if you want to handle long strings exceptionally fast in all browsers".

References

• blog.stevenlevithan.com -- Faster JavaScript Trim

If using jQuery is an option:

/**
 * Trim the site input[type=text] fields globally by removing any whitespace from the
 * beginning and end of a string on input .blur()
 */
$('input[type=text]').blur(function(){
    $(this).val($.trim($(this).val()));
});

or simply:

$.trim(string);

As @ChaosPandion mentioned, the String.prototype.trim method has been introduced into the ECMAScript 5th Edition Specification, some implementations already include this method, so the best way is to detect the native implementation and declare it only if it's not available:

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

Then you can simply:

title = title.trim();

I know this is an old post, but just thought I'd share our solution. In the quest for shortest code (doesn't everyone just love terse regex), one could instead use:

title = title.replace(/(^\s+|\s+$)/g, '');

BTW: I ran this same test through the link shared above blog.stevenlevithan.com -- Faster JavaScript Trim and this pattern beat all the other HANDS down!

Using IE8, added test as test13. The results were:

Original length: 226002
trim1: 110ms (length: 225994)
trim2: 79ms (length: 225994)
trim3: 172ms (length: 225994)
trim4: 203ms (length:225994)
trim5: 172ms (length: 225994)
trim6: 312ms (length: 225994)
trim7: 203ms (length: 225994)
trim8: 47ms (length: 225994)
trim9: 453ms (length: 225994)
trim10: 15ms (length: 225994)
trim11: 16ms (length: 225994)
trim12: 31ms (length: 225994)
trim13: 0ms (length: 226002)

ECMAScript 5 supports trim and this has been implemented in Firefox.

trim - MDC

Here, this should do all that you need

function doSomething(input) {
    return input
              .replace(/^\s\s*/, '')     // Remove Preceding white space
              .replace(/\s\s*$/, '')     // Remove Trailing white space
              .replace(/([\s]+)/g, '-'); // Replace remaining white space with dashes
}

alert(doSomething("  something with  some       whitespace   "));

Here is some methods I've been used in the past to trim strings in js:

String.prototype.ltrim = function( chars ) {
    chars = chars || "\\s*";
    return this.replace( new RegExp("^[" + chars + "]+", "g"), "" );
}

String.prototype.rtrim = function( chars ) {
    chars = chars || "\\s*";
    return this.replace( new RegExp("[" + chars + "]+$", "g"), "" );
}
String.prototype.trim = function( chars ) {
    return this.rtrim(chars).ltrim(chars);
}