<html>
<head>
<script type="text/javascript">

//创建
 var str = "aaafga";
 var str1 = new String("aa");
 var str2= String("aaasdrf");

//属性length
alert(str.length);

//方法charAt()
alert(str2.charAt(3));//s

//方法concat(str1,str2...)
alert(str.concat("dfa","55454"));

//方法indexOf
alert(str.indexOf("a",1));//1

// 方法replace();
alert(str.replace("a","k"));//kaafga

//方法 split();

var st = "1-2-3-5-4-1-2";
var v = st.split("-");
alert(v.length);//7
alert(v[0]);//1


//
</script>

</head>
<body>
  this is my file 
</body>
</html>