Detailed explanation of the steps to implement drop-down box linkage with JS-JS Tutorial-php.cn

Detailed explanation of the steps to implement drop-down box linkage with JS

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Release： 2018-05-22 10:29:13

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This time I will bring you a detailed explanation of the steps to implement drop-down box linkage with JS. What are the precautions for JS to implement drop-down box linkage? The following is a practical case, let's take a look.

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<title> JS下拉联动</title>
<script>
function setSecond(obj){
  var val = obj.value;
  if(val == 'en'){
    var sec = document.getElementById('second');
    sec.innerHTML = "<option>one</option><option>two</option>";
  }else{
    var sec = document.getElementById('second');
    sec.innerHTML = "<option>一</option><option>二</option>";
  }
}
</script>
</head>
<body>
<p>
  <select id="first" onchange="setSecond(this)">
    <option value="en">en</option>
    <option value="zh">zh</option>
  </select>
</p>
<p>
  <select id="second">
  </select>
</p>
</body>
</html>

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Use innerHTML,

IE browser does not support this method, so the improvement method is:

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<title>JS下拉联动</title>
<script>
function setSecond(obj){
  var val = obj.value;
  if(val == 'en'){
    var sec = document.getElementById('second');
    sec.options[0] = new Option("one","one");
    sec.options[1] = new Option("two","two");
  }else{
    var sec = document.getElementById('second');
    sec.options[0] = new Option("一","one");
    sec.options[1] = new Option("二","two");//可设置循环配置，也可一个一个配置
  }
}
</script>
</head>
<body>
<p>
  <select id="first" onchange="setSecond(this)">
    <option value="en">en</option>
    <option value="zh">zh</option>
  </select>
</p>
<p>
  <select id="second">
  </select>
</p>
</body>
</html>

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Can be compatible with Firefox, IE, etc.

I believe you have mastered the method after reading the case in this article. For more exciting information, please pay attention to other related articles on the php Chinese website!