iframe is an inline frame that can embed another document in the current HTML page. Generally, you can use iframe to directly embed the iframe tag in the page and then specify src.
#Some people say that iframe is the element with the highest energy consumption and should be used as little as possible. Some people also say that the security of iframe is too poor and their use should be reduced as much as possible. While what they say is true, the power of iframes cannot be ignored, and there is no shortage of companies using it right now.
<iframe>
The tag specifies an inline frame. An inline frame is used to embed another document within the current HTML document.
All major browsers support the <iframe> tag. You can put the prompt text inside <iframe> and , so that browsers that do not support <iframe> will have the prompt text appear.
How to use iframe?
Usually we use iframe to directly embed the src specified by the iframe tag on the page.
For example:
<!-- <iframe> 标签规定一个内联框架 这里写p 标签是为了看align的效果 --> <p style="overflow: hidden;">这是一些文本。 这是一些文本。 这是一些文本。这是一些文本。 这是一些文本。 这是一些文本。 <iframe name="myiframe" id="myrame" src="external_file.html" frameborder="0" align="left" width="200" height="200" scrolling="no"> <p>你的浏览器不支持iframe标签</p> </iframe> 这是一些文本。 这是一些文本。 这是一些文本。这是一些文本。 这是一些文本。 这是一些文本。</p>
Common attributes of iframe:
name: Specifies the name of <iframe>.
width: Specifies the width of <iframe>.
height: Specifies the height of <iframe>.
src: Specifies the URL of the document displayed in <iframe>.
frameborder: Specifies whether to display the border around <iframe>. (0 means no border, 1 bit has border).
align: Specifies how to align <iframe> based on surrounding elements. (left,right,top,middle,bottom).
scrolling: Specifies whether to display scroll bars in <iframe>. (yes,no,auto)
The src attribute of the iframe in the above code is a local html page
The code is as follows:
<body> <div id="div" style="height: 300px; background: #ddd;">这是一个外部文件里面的内容</div></body><script> var div = document.getElementById("div"); console.log(div);</script>
Yes The interactive parts are also written into this page, and the iframe will be automatically transferred to the imported page.
How to get the content inside the iframe?
var iframe = document.getElementById("myrame"); //获取iframe标签 var iwindow = iframe.contentWindow; //获取iframe的window对象 var idoc = iwindow.document; //获取iframe的document对象 console.log(idoc.documentElement); //获取iframe的html console.log("body",idoc.body);
However, the DOM inside cannot be obtained. It can be obtained from the URL (that is, the imported html file)
Advantages and Disadvantages of iframe
Advantages:
When reloading a page, you do not need to reload the entire page. You only need to reload a frame page in the page (reduce data transmission, reduce The loading time of the web page);
The technology is simple and easy to use, and it is mainly used for pages that do not require search engines to search;
It is convenient for development and reduces the duplication rate of code (such as the header of the page, footer);
Disadvantages:
will generate a lot of pages, which is not easy to manage;
is not easy to print;
Multiple frames The page will increase the service and make http requests;
The browser's back button is invalid, etc.;
Due to many shortcomings and does not conform to the concept of standard web design, it has been abandoned, and the current HTML5 This tag is no longer supported.
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