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js method to detect whether iframe is loaded_javascript skills

WBOYOriginal: 2016-05-16 15:29:391117browse

The example in this article describes the method of js detecting whether the iframe is loaded. Share it with everyone for your reference, the details are as follows:

Here is an extension application following the previous article "JS method to implement iframe frame value (compatible with IE, firefox, chrome, etc.) ":

Application scenario: One of the most unique applications of iframe in my opinion is that it can achieve cross-domain writing of cookies with the P3P protocol (it seems that apart from this, a more effective way has not been found), but sometimes we don’t know this Whether the iframe page has been executed, is there any way to determine whether the page in the iframe has been loaded?

iframe1.html:

<html>
<head>
  <title>框架内页</title>
</head>
<body>
  <div>
    <input id="txt" name="txt" type="text" value="3秒钟后这里会变成ok" />
  </div>
  <script type="text/javascript">
    setTimeout("SetValue()",3000);
    function SetValue(){
      document.getElementById("txt").value="ok";
    }
  </script>
</body>
</html>

iframe2.html:

<html>
<head>
  <title>框架内页</title>
</head>
<body>
  <div>
    <input id="txt" name="txt" type="text" value="6秒钟后这里会变成ok" />
  </div>
  <script type="text/javascript">
    setTimeout("SetValue()",6000);
    function SetValue(){
      document.getElementById("txt").value="ok";
    }
  </script>
</body>
</html>

index.html:

<html>
<head>
  <title>检测本页中的所有iframe是否加载完成</title>
  <script type="text/javascript">
//得取iframe中的某个html控件值
function getIframeControlValue(iframeId,controlId){
  var ofrm = document.getElementById(iframeId).document;
  if (ofrm==undefined)
  {
    ofrm = document.getElementById(iframeId).contentWindow.document;
    var ff = ofrm1.getElementById(controlId).value;
    return ff;
  }
  else
  {
    var ie = document.frames[iframeId].document.getElementById(controlId).value;
    return ie;
  } 
}
//检测所有的iframe是否"加载"完成
function fnLoadOk(){
  var b = true;
  for(var i=1;i<=2;i++){
    if (getIframeControlValue("frame" + i,"txt")=="ok"){
      b = b && true;
    }
    else
    {
      b = b && false;
    }
  }
  return b;
}
//设置回答显示区的值
function setValue(str){
  if (str!=null && str.length>0){
    document.getElementById("result").innerHTML = "<span style='color:red'>" + new Date().toLocaleString() + " " + str + "</span>";
  }
  else{
    document.getElementById("result").innerHTML = "<span style='color:green'>" + new Date().toLocaleString() + " 正在加载" + "</span>";
  }  
}
var _check = setInterval("t()",500);//每隔0.5秒检查一次
function t(){
  if (fnLoadOk()){
    clearInterval(_check);//加载完成后，清除定时器
    setValue("加载完成!");
  }
  else{
    setValue();
  }
}
</script>
</head>
<body>
<h3>检测本页中的iframe是否加载完成</h3>
<iframe name="frame1" id="frame1" src="iframe1.html" frameborder="1" height="60" width="180"></iframe>
<iframe name="frame2" id="frame2" src="iframe2.html" frameborder="1" height="60" width="180"></iframe>
<div id="result" style="margin:10px;">
准备就绪
</div>
</body>
</html>

It is worth noting that the example in this article is detected in the button click event. If you plan to start detection as soon as the page is opened, it must be placed in the onload event of the index.html page body, otherwise an exception will occur ( The reason is that index.html has not been loaded yet. At this time, we rush to get the content of the frame, and what we get is undefined or null)

I hope this article will be helpful to everyone in JavaScript programming.

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