Usage and precautions of iframe_Experience exchange

This article mainly talks about the usage and precautions of iframe:
Many comrades do not know very much about how iframe is controlled, and they are basically still in a vague state of understanding.
Pay attention to two things, ifr is the ID and NAME value of an existing iframe:
 document.getElementById(“ifr”);
 window.frames[“ifr”];

To use iframe function, the variables must go through the second method. Because it takes a complete DOM model (I don’t know if this is correct). The first method just takes out an OBJECT.

If only If you want to change the iframe's src or border, scrolling and other attributes (which are not the same concept as property, property cannot be written in tags, such as: scrollHeight, innerHTML, etc.), you need to use the first method.

If you want to get the iframe page (not the iframe itself), you need to use the second method, because it gets a complete DOM model. For example, if you want to get the content of the iframe's document.body, you can only use the second method.

Also note that if you call the iframe's DOM model when the iframe page is not fully loaded, a serious error will occur, so you need to prepare a fault-tolerant mode.
The following are examples, one is aa.htm and the other is bb.htm. Please check that it is running locally first. I don’t need to explain the reasons!

aa.htm

<title>Untitled Page</title> <style type="text/css"> <!-- body{ margin:0px; } --> </style> <iframe id="ifr" name="ifr" width="100%" height="500" src="bb.htm"></iframe> <script language="javascript" type="text/javascript"> var aa_value="I'm a variant in Top window!"; var ifr_id=document.getElementById("ifr"); var ifr_window=window.frames["ifr"]; alert("Alert from Top window : Can't get iframe's variant by ifr_id, it will return :" + ifr_id.bb_var); alert("Alert from Top window : Can't get iframe's DOM model by ifr_id ,it will return :" + ifr_id.window); alert("Alert from Top window : Get src from id :" + ifr_id.src); alert("Alert from Top window : Get href from window:" + ifr_window.document.location.href); //由于bb.htm可能还未装载完成,所以,下冇的可能引发错误 //调用iframe内的函数 ifr_window.bb(); //调用iframe内的变量 alert("Alert from Top window : " + ifr_window.bb_var); // alert("Alert from Top Window :" + ifr_window.document.body.innerHTML); function aa(msg){ alert("I'm alerting from Top window ,and I received a msg:\n" + msg); } </script>
[Ctrl A Select all Note:If you need to introduce external Js, you need to refresh it to execute]

bb.htm

<title>sub frame</title> <style type="text/css"> <!-- html,body{ margin:0px; width:90%; } --> </style> I'm a sub frame! ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... <script language="javascript" type="text/javascript"> var bb_var="I'm a variable in ifr"; function bb(){ alert("Alert from iframe :I'm frame ifr's function") } //获取父页面的变量 alert("Alert from iframe parent.ifr_id::" + parent.ifr_id); alert("Alert from iframe parent.aa_value : " + parent.aa_value); //通过父页面的ifr_id来改变 iframe的高度 alert("Alert from iframe : ifr's clientHeight :" +document.body.clientHeight); parent.ifr_id.height=document.body.clientHeight; alert("Alert from iframe : ifr's scrollHeight : " + document.body.scrollHeight); //调用父窗体的函数: parent.aa("I will calling a function which is Top window's "); //改变父窗体的标题: alert("Alert from iframe : I will changing Top window's title"); top.document.title="The title value changed"; //通过父窗体的ifr_id来改变的border 与scrolling alert("Alert from iframe : I will change my border and scrolling :"); top.ifr_id.border=0; top.ifr_id.scrolling="no"; </script>
[Ctrl A 全选 注:如需引入外部Js需刷新才能执行]