Simple JavaScript code for determining whether a web page is in an iframe

The following is a simple JavaScript code snippet to check if the window is in an iframe. It is useful for some functions that may use URLs in the page's address bar. The code is as follows:

var isInIframe = (window.location != window.parent.location) ? true : false;

Related readings:

• Get the source of injected iframe href
• How to reload iframe

FAQs about jQuery and iframes (FAQ)

How to use jQuery to check if a web page is loaded in an iframe?

To use jQuery to check if the web page is loaded in an iframe, you can use the window.self and window.top properties. If the web page is loaded in an iframe, window.self will not equal window.top. Here is a simple code snippet:

if (window.self !== window.top) {
  // 網(wǎng)頁在 iframe 內(nèi)
} else {
  // 網(wǎng)頁不在 iframe 內(nèi)
}

What is the difference between window.self and window.top in JavaScript?

In JavaScript, window.self refers to the current window, while window.top refers to the top-level window in the window hierarchy. If the web page is loaded directly in the browser, window.self and window.top will be the same. However, if the web page is loaded within an iframe, window.self will refer to the iframe window, and window.top will refer to the main browser window.

Can I use jQuery to operate the content inside an iframe?

Yes, you can use jQuery to operate the content inside an iframe. However, due to the same-origin policy, this can only be done if the iframe and the parent document are from the same domain. Here is an example of how to change the HTML of the body tag inside an iframe:

$("#myIframe").contents().find("body").html("Hello, World!");

How to detect iframes using pure JavaScript without jQuery?

You can use pure JavaScript to detect iframes by comparing window.self and window.top, which is similar to the jQuery method. The method is as follows:

if (window.self !== window.top) {
  // 網(wǎng)頁在 iframe 內(nèi)
} else {
  // 網(wǎng)頁不在 iframe 內(nèi)
}

What is a homologous policy and how does it affect an iframe?

Same-origin policy is a security feature implemented in a web browser that prevents scripts from interacting with each other. This policy affects the iframe because it prevents scripts in the parent document from accessing or manipulating the content inside the iframe (if they are not from the same domain).

Can I bypass the same-origin policy to access iframes from different domains?

Bypassing homologous policies is usually not recommended for security reasons. However, if you control the parent document and iframe content, you can use the document.domain attribute or postMessage method to communicate between the two.

How to use the postMessage method to communicate between an iframe and a parent document?

postMessage method allows you to send data between windows, even if they are not from the same domain. Here is an example of how to use it:

var isInIframe = (window.location != window.parent.location) ? true : false;

Can I use jQuery in all browsers to detect if a webpage is loaded inside an iframe?

Yes, the method of comparing window.self and window.top works for all modern browsers, including Chrome, Firefox, Safari, and Edge.

Can I load a web page in an iframe using jQuery?

Yes, you can use the attr method in jQuery to set the src property of the iframe to load the web page in the iframe. Examples are as follows:

if (window.self !== window.top) {
  // 網(wǎng)頁在 iframe 內(nèi)
} else {
  // 網(wǎng)頁不在 iframe 內(nèi)
}

Can I use jQuery to resize the iframe according to its content?

Yes, you can use jQuery to resize the iframe according to its content. However, due to the same-origin policy, this can only be done if the iframe and the parent document are from the same domain. Examples are as follows:

$("#myIframe").contents().find("body").html("Hello, World!");

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