Analyze iframe applications and principles-HTML Tutorial-php.cn

Analyze iframe applications and principles

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Release： 2024-01-06 08:19:08

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Analyze iframe applications and principles

Application and principle analysis of iframe

With the development of the Internet, the functionality and complexity of web pages are becoming higher and higher. In order to meet the needs of users, developers need to integrate different web content into one page, and this is where iframes come in handy. This article will provide a detailed analysis of the application and principles of iframe and provide specific code examples.

1. Basic concepts of iframe
1.1 What is iframe?
iframe (short for Inline Frame) is an HTML element that allows another HTML document to be embedded into the current document. It can be understood as a small window used to display the content of other web pages.

1.2 Basic syntax of iframe
In HTML, create an iframe by using the tag. For example:

<iframe src="http://www.example.com"></iframe>

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The above code will create an iframe in the current document, which will load the web page content of the specified URL.

2. Application scenarios of iframe
2.1 Content display under the same domain name
The most common application scenario is to display the content of different web pages under the same domain name on one page. For example, the homepage of an e-commerce website can use iframe to display the latest product activities, popular recommendations and other content on the homepage.

2.2 Display of content under cross-domain names
In addition to displaying content under the same domain name, iframe can also be used to display content under cross-domain names. For example, a news aggregation website can use iframes to integrate content from major news media on the same page.

2.3 Code snippet display
Developers often need to display a piece of code in a blog or article, but directly posting the code is not beautiful and easy to read. At this time, you can use an iframe to display code snippets, and load the code snippets by setting the src attribute of the iframe so that they can be displayed in preview form in blogs or articles.

3. Analysis of the principle of iframe
3.1 Working principle of iframe
When the browser encounters the tag, it will create a window corresponding to the tag and load it according to the src attribute The content of the specified URL web page. This window is similar to a pop-up window, but unlike an ordinary browser window, it is independent of the current page. </p><p>3.2 Interaction between iframe and current page<br>Since iframe and current page are independent, there is a cross-domain access problem between the two. Even if a web page with the same domain name is loaded in the iframe, its content cannot be accessed directly through JavaScript. </p><p>However, cross-domain communication can be achieved through the postMessage method of the window object. The postMessage method allows messages to be sent between different windows, thereby enabling interaction between the iframe and the current page. </p><p>4. Specific code examples of iframe<br>The following are specific code examples for the content display of iframe and web pages under the same domain name, the content display of web pages under cross-domain names, and the code snippet display. </p><p>4.1 Example of displaying web page content under the same domain name</p><div class="code" style="position:relative; padding:0px; margin:0px;"><div class="code" style="position:relative; padding:0px; margin:0px;"><pre class='brush:php;toolbar:false;'><iframe src="http://www.example.com"></iframe></pre><div class="contentsignin">Copy after login</div></div><div class="contentsignin">Copy after login</div></div><p>The above code will create an iframe in the current document and load the content of the http://www.example.com web page. </p><p>4.2 Example of displaying web page content under cross-domain names</p><div class="code" style="position:relative; padding:0px; margin:0px;"><pre class='brush:php;toolbar:false;'><iframe src="http://www.otherdomain.com"></iframe></pre><div class="contentsignin">Copy after login</div></div><p>The above code will create an iframe in the current document and load the content of the http://www.otherdomain.com web page. </p><p>4.3 Example of code snippet display</p><div class="code" style="position:relative; padding:0px; margin:0px;"><pre class='brush:php;toolbar:false;'><iframe srcdoc=" <html> <body> <pre class="brush:php;toolbar:false"> <code> function sayHello() { console.log('Hello!'); } sayHello(); </code> </pre><div class="contentsignin">Copy after login</div></div> </body> </html> ">

The above code will create an iframe in the current document and display the specified HTML code as its content.

Summary:
Through the above analysis of the application and principle of iframe, we can see that iframe is a very useful HTML element that can realize the integrated display of different web page content. Whether it is content display under the same domain name or content display under cross-domain names, it can be achieved through iframe. At the same time, we also learned that the interaction between iframe and the current page can be achieved through the postMessage method. I hope this article will help you further understand and apply iframe.

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