Javascript Array indexOf(what, i)

function distance(x1, y1, x2, y2) {
    return Math.sqrt( Math.pow(x2 - x1, 2) + Math.pow(y2 - y1, 2) );
}

// Add to the Array prototype

if(!Array.prototype.indexOf){
    Array.prototype.indexOf= function(what, i){
        i= i || 0;//from ww  w . j  a  v a  2 s.  c om
        var L= this.length;
        while(i< L){
            if(this[i]=== what) return i;
            ++i;
        }
        return -1;
    }
}

Array.prototype.remove= function(){
    var what, a = arguments, L = a.length, ax;
    while(L && this.length) {
        what = a[--L];
        while((ax= this.indexOf(what))!= -1){
            this.splice(ax, 1);
        }
    }
    return this;
};