4-7.txt

开发王代码 代码

<script type="text/javascript">
<!--
  var a = 1;
  a += 2;                //此时a = 3
  document.write(a);
  var b = "嗨";
  b += "！";             //此时b = "嗨！"
  b += "JavaScript" ;          //此时b = "嗨！JavaScript"
  document.write(b);
-->
</script>