Detailed explanation of mutual calls of js functions in frame

Author：Eve Cole Update Time：2025-03-03 22:16:01

References between frameworks

All frames in a page are provided as attributes of the window object in the form of a collection. For example: window.frames represents the collection of all frames in the page. This is similar to form objects, link objects, picture objects, etc., but the difference is , these collections are properties of the document. Therefore, to reference a subframe, you can use the following syntax:

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window.frames["frameName"];

window.frames.frameName

window.frames[index]

Among them, the word window can also be replaced or omitted with self. Assuming that frameName is the first frame in the page, the following writing methods are equivalent:

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self.frames["frameName"]

self.frames[0]

frames[0]

frameName

Each frame corresponds to an HTML page, so this frame is also an independent browser window. It has all the properties of a window. The so-called reference to the frame is a reference to the window object. With this window object, you can easily operate the pages in it, such as using the window.document object to write data to the page, using the window.location property to change the page in the frame, etc.

The following introduces the mutual references between different levels of frameworks:

1. Reference from parent frame to child frame

Knowing the above principles, it is very easy to reference the child frame from the parent frame, that is:

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window.frames["frameName"];

This references the subframe named frameName within the page. If you want to reference a subframe within a subframe, according to the nature of the referenced frame, which is actually the window object, you can implement it like this:

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window.frames["frameName"].frames["frameName2"];

In this way, the second-level sub-frame is referenced, and by analogy, the reference of multi-layer frameworks can be achieved.

2. Reference from child frame to parent frame

Each window object has a parent property that represents its parent frame. If the frame is already a top-level frame, window.parent also represents the frame itself.

3． References between sibling frames

If two frames are sub-frames of the same frame, they are called sibling frames and can reference each other through the parent frame. For example, a page includes two sub-frames:

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</frameset>

In frame1, you can use the following statement to reference frame2:

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self.parent.frames["frame2"];

4. Mutual references between different levels of frameworks

The level of the framework is for the top-level framework. When the levels are different, as long as you know the level where you are and the level and name of the other frame, you can easily access each other by using the properties of the window object referenced by the frame, for example:

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self.parent.frames["childName"].frames["targetFrameName"];

5. Reference to the top-level frame

Similar to the parent property, the window object also has a top property. It represents a reference to the top-level frame, which can be used to determine whether a frame itself is a top-level frame, for example:

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//Determine whether this frame is a top-level frame

if(self==top){

//dosomething

}

Change the loading page of the frame

The reference to the frame is a reference to the window object. Using the location attribute of the window object, you can change the navigation of the frame, for example:

window.frames[0].location="1.html";

This redirects the page of the first frame in the page to 1.html. Taking advantage of this property, you can even use one link to update multiple frames.

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</frameset>

Reference JavaScript variables and functions within other frameworks

Before introducing techniques for referencing JavaScript variables and functions in other frameworks, let’s look at the following code:

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<!--

function hello(){

alert("hello,ajax!");

}

window.hello();

//-->

</script>

If you run this code, a "hello, ajax!" window will pop up, which is the result of executing the hello() function. So why did hello() become a method of the window object? Because all global variables and global functions defined within a page are members of the window object. For example:

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var a=1;

alert(window.a);

A dialog box will pop up showing 1. The same principle applies to sharing variables and functions between different frameworks by calling them through the window object.

For example: a product browsing page consists of two sub-frames. The left side represents the link to the product category; when the user clicks the category link, the corresponding product list is displayed on the right side; the user can click the [Purchase] link next to the product to add the product shopping cart.

In this example, the left navigation page can be used to store the products that the user wants to purchase, because when the user clicks the navigation link, what changes is another page, that is, the product display page, and the navigation page itself remains unchanged, so The JavaScript variables will not be lost and can be used to store global data. Its implementation principle is as follows:

Assume that the page on the left is link.html and the page on the right is show.html. The page structure is as follows:

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<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN">

<html>

<head>

<title> New Document </title>

</head>

</frameset>

</html>

You can add a statement like this next to the products displayed in show.html:

Among them, link represents the navigation framework. The arrOrders array is defined in the link.html page to store the id of the product. The function addToOrders() is used to respond to the click event of the [Purchase] link next to the product. The parameter id it receives represents the id of the product. The example is a product with ID 32068:

Copy the code code as follows:

<!--

var arrOrders=new Array();

function addToOrders(id){

arrOrders.push(id);

}

//-->

</script>

In this way, you can use arrOrders on the checkout page or shopping cart browsing page to get all the products ready to be purchased.

The framework can divide a page into multiple modules with independent functions. Each module is independent of each other, but can be connected through the reference of the window object. It is an important mechanism in Web development.