Question

How can I implement a function that does the same thing as ArrayList.remove(o)?

The closest thing I have is

Array.prototype.remove = function(o) {
    var index = this.indexOf(o);
    if(index == -1) {
        return;
    }
    return this.splice(index, index);
}

However it throws an error on the second line, claiming indexOf(o) doesn’t exist. (cannot find function indexOf())

Answer 1

Array.prototype.indexOf is not supported by IE7 and below. So you would need to shim that method aswell before, like

Array.prototype.indexOf = Array.prototype.indexOf || function( search ) {
    for(var i = 0, len = this.length; i < len; i++) {
        if( this[ i ] === search ) {
            return i;
        }
    }
    return -1;
};

^{(simplified example)}.

Furthermore, your call to .splice() is wrong, second argument is the length of elements you want to remove and it should be 1.

Array.prototype.remove = function(o) {
    var index = this.indexOf(o);
    if(~index) {
        this.splice(index, 1);
    }
};