Remove CSS class from element with JavaScript (no jQuery)

document.getElementById("MyID").className =
    document.getElementById("MyID").className.replace(/\bMyClass\b/,'');

where MyID is the ID of the element and MyClass is the name of the class you wish to remove.

function hasClass(ele,cls) {
    return ele.className.match(new RegExp('(\\s|^)'+cls+'(\\s|$)'));
}

function removeClass(ele,cls) {
        if (hasClass(ele,cls)) {
            var reg = new RegExp('(\\s|^)'+cls+'(\\s|$)');
            ele.className=ele.className.replace(reg,' ');
        }
    }

Here's a way to bake this functionality right into all DOM elements:

HTMLElement.prototype.removeClass = function(remove) {
    var newClassName = "";
    var i;
    var classes = this.className.split(" ");
    for(i = 0; i < classes.length; i++) {
        if(classes[i] !== remove) {
            newClassName += classes[i] + " ";
        }
    }
    this.className = newClassName;
}

Actually, the right way (standard) to do (but only works with Firefox3.6):

ELEMENT.classList.remove("CLASS_NAME");

I'm going to publish an article about that on http://hacks.mozilla.org next week with fallback mechanism for other browsers.

Documentation: https://developer.mozilla.org/en/DOM/element.classList

try:

function removeClassName(elem, name){
    var remClass = elem.className;
    var re = new RegExp('(^| )' + name + '( |$)');
    remClass = remClass.replace(re, '$1');
    remClass = remClass.replace(/ $/, '');
    elem.className = remClass;
}

Check this out: http://stackoverflow.com/questions/195951/change-an-elements-css-class-with-javascript

This answer has some good examples.

Patrick.

div.classList.add("foo");
div.classList.remove("foo");

More at https://developer.mozilla.org/en-US/docs/Web/API/element.classList

It's very simple, I think.

document.getElementById("whatever").classList.remove("className");

All of these answers are way too complicated, try

var string = "Hello, whats on your mind?";
var new_string = string.replace(', whats on your mind?', '');

The result would be a return of the string

Hello

Super easy. Credits go to jondavidjohn Remove portion of string in Javascript

I was just working with something like this. Here's a solution I came up with...

// Some browsers don't have a native trim() function
if(!String.prototype.trim) {
    Object.defineProperty(String.prototype,'trim', {
        value: function() {
            return this.replace(/^\s+|\s+$/g,'');
        },
        writable:false,
        enumerable:false,
        configurable:false
    });
}
// addClass()
// first checks if the class name already exists, if not, it adds the class.
Object.defineProperty(Node.prototype,'addClass', {
    value: function(c) {
        if(this.className.indexOf(c)<0) {
            this.className=this.className+=' '+c;
        }
        return this;
    },
    writable:false,
    enumerable:false,
    configurable:false
});
// removeClass()
// removes the class and cleans up the className value by changing double 
// spacing to single spacing and trimming any leading or trailing spaces
Object.defineProperty(Node.prototype,'removeClass', {
    value: function(c) {
        this.className=this.className.replace(c,'').replace('  ',' ').trim();
        return this;
    },
    writable:false,
    enumerable:false,
    configurable:false
});

Now you can call myElement.removeClass('myClass')

or chain it: myElement.removeClass("oldClass").addClass("newClass");

There is also $.toggleClass, $.addClass, and $.removeClass. For documentation, take a look at http://api.jquery.com/toggleClass/.

Take a look at this jsFiddle example to see it in action.