Element.hasAttribute()

The Element.hasAttribute() method returns a Boolean value indicating whether the specified element has the specified attribute or not.

var result = element.hasAttribute(name);

result

holds the return value true or false.

name

is a string representing the name of the attribute.

var foo = document.getElementById("foo");
if (foo.hasAttribute("bar")) {
    // do something
}

;(function(prototype) {
    prototype.hasAttribute = prototype.hasAttribute || function(name) {
        return !!(this.attributes[name] &&
                  this.attributes[name].specified);
    }
})(Element.prototype);