javascript String.indexOf實現

群裡abcd提出問題,現在有以下三個實現，歡迎大家參與(注意，為了相容IE6，不能使用str[i]，要用str.charAt(i);不能使用slice，replace等原生函數)：

GrayZhang的實現

String.prototype.substring = function(start, length) {    var array = [];    for (var i = start; i 
我的實現：
//by 司徒正美 2011.8.18String.prototype.indexOf = function(sub){        var a = sub.charAt(0),an = sub.length,n = this.length;        if(n == an){          return this == sub ? 0 : -1        }        if(n <p>abcd的實現：</p><pre class="brush:js;gutter:false;toolbar:false;">function indexOf(s, t) {if (s.length) {var back = false;var i = 0;for (var j = 0; j < t.length; ++j) {if (s.charAt(i) != t.charAt(j)) {do {if (++i >= s.length) return -1;if (s.charAt(i) == t.charAt(j)) {if (j) back = true;break;}}while (true);}if (back) {for (var k = 1; k <= j; k++)if (s.charAt(i - k) != t.charAt(j - k))continue;back = false;}}return i - j + 1;}return t.length && -1;} </pre><p>http://proto.layer51.com/d.aspx?f=32</p><p>//---------------------------------------------------------------------------<br />String.prototype.charAt = function(index){<br />    return(substring(this, index+1, 1));<br />}  </p><p>String.prototype.concat = function(){<br />    var r = this.toString();<br />    for (var i=0; i= 0) && (substring(this, i--, size) != sub));<br />    return (i == -1 ? -1 : (i));<br />}  </p><p>String.prototype.slice = function(s, e){<br />    return(substring(this, s+1, e-s));<br />}  </p><p>String.prototype.split = function(d){<br />    if (d != null){<br />        var r = new Array();<br />        var size = this.length;<br />        var c = 0;<br />        var n = 0;<br />        if (d != ""){<br />            for (var i=0; i96 && upNo223 && upNo64 && upNo191 && upNo</p><p></arguments.length>