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js 觸發select onchange事件代碼

 select 或text的onchange事件需要手動(通過鍵盤輸入)改變select或text的值才能觸發,本文為大家介紹下使用js觸發select onchange事件

select 或text的onchange事件需要手動(通過鍵盤輸入)改變select或text的值才能觸發,如果在js中給select或text賦值,則無法觸發onchang事件,  例如,在頁面加載完成以後,需要觸發一個onChange事件,在js中用document.getElementById("province").value="湖北";直接給select或text賦值是不行的,要想實現手動觸發onchange事件,需要在js給select賦值後,加入下面的語句    document.getElementById("province").fireEvent('onchange') 來實現,  代碼如下: <head>  <meta http-equiv="Content-Type" content="text/html; charset=gb2312" />  <title>無標題文檔</title>  <script type="text/javascript">  var provinces = new Array();  provinces["湖北"] = ["武漢","襄陽","隨州","宜昌","十堰"];  provinces["四川"] = ["成都","內江","達州"];  provinces["河南"] =["鄭州","南陽","信陽","漯河"];  function changeProvince()  {  var prov = document.getElementById("province").value;  var city =document.getElementById("city");  city.options.length =0;  for(var i in provinces[prov])  {  city.options.add(new Option(provinces[prov][i],provinces[prov][i]));  }  }  window.onload = function(){  var province = document.getElementById("province");    for(var index in provinces)  {  //alert(index);  province.options.add(new Option(index,index));  }  province.fireEvent("onchange");  };  </script>  </head>  <body>  省份:<select id="province" onchange= "changeProvince()"></select>  城市:<select id="city"></select>  </body>  </html> 
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