1 var box = "this is javascript"; 2 for (var i = -1, arr = []; (i = box.indexOf("s", i + 1)) > -1; arr.push(i)); 3 alert(arr);
其原理还可以这样理解：
var str ="this is javascript"
var resault ={index:"",count:0};
while ( true ){
var index = str.indexOf("s") ;
if(index == -1) break;
resault.index += index +",";
reaault.count++;
}
resault.index = index.subString(0,resault.index.length-1);
console.log("index:"+resault.index);
console.log("count:"+reaault.count);
原文：http://www.cnblogs.com/webSong/p/6339687.html