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How to implement javascript to pop up a warning box when the check box exceeds the limit_javascript skills

WBOY
WBOYOriginal
2016-05-16 16:13:111474browse

The example in this article describes the method of using JavaScript to pop up a warning box when the check box exceeds the limit. Share it with everyone for your reference. The specific implementation method is as follows: 

<html>
<title>javascript实现复选框超过限制即弹出警告框的方法</title>
<body>
<SCRIPT LANGUAGE="JavaScript">
<!--//
function countChoices(obj) {
max = 2;
box1 = obj.form.box1.checked;
box2 = obj.form.box2.checked;
box3 = obj.form.box3.checked;
count = (box1 &#63; 1 : 0) + (box2 &#63; 1 : 0) + (box3 &#63; 1 : 0);
if (count > max) {
alert("对不起，你只能选择" + max + "个项目!");
obj.checked = false;
  }
}
//-->
</script>
   <form name="form">
    请最多选择2个项目： 
    <p> 
     <input type=checkbox name=box1 onClick="countChoices(this)">
     选择项目1
    <p> 
     <input type=checkbox name=box2 onClick="countChoices(this)">
     选择项目2
    <p> 
     <input type=checkbox name=box3 onClick="countChoices(this)">
     选择项目3
    <p> 
   <div>
</div>
</FORM>
</body>
</html>

I hope this article will be helpful to everyone’s JavaScript programming design.

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