indexof-min.js

if(!Array.prototype.indexOf){Array.prototype.indexOf=function(b){var a=this.length>>>0;var c=Number(arguments[1])||0;c=(c<0)?Math.ceil(c):Math.floor(c);if(c<0){c+=a}for(;c<a;c++){if(c in this&&this[c]===b){return c}}return -1}};

indexof.js

if (!Array.prototype.indexOf) {
  Array.prototype.indexOf = function(elt /*, from*/) {
    var len = this.length >>> 0;
    var from = Number(arguments[1]) || 0;
    from = (from < 0)
         ? Math.ceil(from)
         : Math.floor(from);
    if (from < 0)
      from += len;

    for (; from < len; from++) {
      if (from in this &&
          this[from] === elt)
        return from;
    }
    return -1;
  };
}

http://www.youtube.com/watch?v=hQVTIJBZook#t=1840s