A brief analysis of several ways to obtain parent page elements or data using jquery

jQuery is a commonly used JavaScript library because it simplifies the development of many tasks such as HTML document traversal and event handling.

In some cases, JavaScript needs to communicate with the iframe or parent page, and in this case it is necessary to obtain elements or data in the parent page. Here are several methods to obtain parent page elements or data.

1. parent object

The parent page can use the parent object to access the current page, and the child page can also access the parent page through window.parent. Use parent to get all elements and attributes of the parent page. Suppose there is a parent page that contains an iframe element named myIframe. The child page can use the following code to obtain all h1 tags in the parent page:

var h1s = parent.$("h1");

2. window.top object

top object can also be used to access the parent page. It provides access to the entire page hierarchy, through which the entire window can be accessed. You can use top to access elements and attributes in the parent page.

Compared with parent, the main advantage of using top is cross-domain. If the parent page and child page have different domain names, use top to bypass cross-domain security restrictions.

var h1s = window.top.$("h1");

3. Using the postMessage method

postMessage is a new method introduced by HTML5, which is used to safely deliver messages between two windows. When using the postMessage method, the child page can send messages to the parent page, and the parent page can listen to these messages.

Sub page code:

window.parent.postMessage("Hello from iframe!", "*");

In the parent page, you can listen to messages and obtain elements or data in the parent page as needed:

window.addEventListener("message", function(event) {
  if (event.source != window.parent) return;

  // 获取消息的内容
  var data = event.data;

  // 在父页面中查找h1元素
  var h1s = $('h1', event.source.document);
}, false);

4. Use window .opener property (pop-up windows only)

If a child page is opened in a pop-up window, you can use the window.opener property to access the object of the opened parent window.

var h1s = window.opener.$("h1");

In short, no matter which method is used, cross-domain permissions are required to obtain parent page elements or data. When using cross-domain functionality, make sure to implement security and follow best practices.

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