分割字符串
<script type="text/javasript">
var str="how are you doing today"
document.write(str.spilt(" ")+<br />);
document.write(str.spilt("")+<br />);
document.write(str.spilt(" "),3);
</script>
how,are,you,doing,today
h,o,w, ,·······
how,are,you