Overview of Frame Programming An HTML page can have one or more sub-frames, which are marked with and are used to display an independent HTML page. The framework programming discussed here includes self-control of frameworks and mutual access between frameworks, such as referencing JavaScript variables in another framework from one framework, calling functions in other frameworks, controlling the behavior of forms in another framework, etc. <br><br><strong>Mutual references between frames</strong> <br>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 attributes of all frames in the page. Collections are similar to form objects, link objects, picture objects, etc. The difference is that these collections are attributes of the document. Therefore, to reference a subframe, you can use the following syntax: <br>window.frames["frameName"]; <br>window.frames.frameName <br>window.frames[index] <br>where the word window is also You can use self instead or omit it. Assuming that frameName is the first frame in the page, the following writing methods are equivalent: <br>self.frames["frameName"] <br>self.frames[0] <br>frames [0] <br>frameName <br>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 also 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. <br><br><strong>The following introduces the mutual references between different levels of frameworks: </strong> <br><br>1. Reference from parent frame to child frame <br> Knowing the above principles, it is very easy to reference the child frame from the parent frame, that is: <br>window.frames["frameName"]; <br>In this way, the name within the page is referenced is the subframe of frameName. If you want to reference a subframe within a subframe, according to the nature of the window object, the referenced frame can be implemented like this: <br>window.frames["frameName"].frames["frameName2"]; <br>This is how to reference When it comes to the second-level sub-framework, and so on, the reference of multi-layer frameworks can be achieved. <br><br>2． Reference from child frame to parent frame <br>Each window object has a parent attribute that represents its parent frame. If the frame is already a top-level frame, window.parent also represents the frame itself. <br><br>3． References between sibling frames <br> If two frames are sub-frames of the same frame, they are called sibling frames. They can reference each other through the parent frame. For example, a page includes 2 sub-frames: <br></p> <div class="codetitle"> <span><a style="CURSOR: pointer" data="81594" class="copybut" id="copybut81594" onclick="doCopy('code81594')"><u>Copy code</u></a></span> The code is as follows:</div> <div class="codebody" id="code81594"> <br><frameset rows="50%,50%"> <br>< frame src="1.html"name="frame1" /> <br><frame src="2.html"name="frame2" /> <br></frameset> <br> </div> <br>You can use the following statement in frame1 to reference frame2: <br>self.parent.frames["frame2"]; <br><br>4. Mutual references between different levels of frameworks <br>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: <br>self.parent.frames["childName "].frames["targetFrameName"]; <br><br>5． The reference to the top-level frame <br> is similar to the parent attribute. The window object also has a top attribute. 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: <br><div class="codetitle"> <span><a style="CURSOR: pointer" data="73308" class="copybut" id="copybut73308" onclick="doCopy('code73308')"><u>Copy code</u></a></span> Code As follows: </div> <div class="codebody" id="code73308"> <br>//Determine whether this frame is a top-level frame<br>if(self==top){ <br>//dosomething <br>} <br> </div> <br> <strong>Change the loading page of the frame</strong> <br>The reference to the frame is the reference to the window object. Using the location attribute of the window object, you can change the navigation of the frame, for example: <br>window.frames[0] .location="1.html"; <br>This will redirect the page of the first frame in the page to 1.html. Using this property, you can even use one link to update multiple frames. <br><div class="codetitle"> <span><a style="CURSOR: pointer" data="51282" class="copybut" id="copybut51282" onclick="doCopy('code51282')"><u>Copy code</u></a></span> The code is as follows:</div> <div class="codebody" id="code51282"> <br><frameset rows="50%,50%" > <br><frame src="1.html"name="frame1" /> <br><frame src="2.html"name="frame2" /> <br></ frameset> <br><!--somecode--> <br><a href="frame1.location='3.html;frame2.location='4.html'"onclick="">link< ;/a> <br><!--somecode--> <br> </div> <br>Referencing JavaScript variables and functions in other frameworks<br>Before introducing the techniques of referencing JavaScript variables and functions in other frameworks, let’s take a look at the following code: <br><div class="codetitle"> <span><a style="CURSOR: pointer" data="90803" class="copybut" id="copybut90803" onclick="doCopy('code90803')"><u> Copy the code </u></a></span> The code is as follows: </div> <div class="codebody" id="code90803"> <br><script language="JavaScript" type="text/javascript"> <br><!-- <BR>function hello(){ <BR>alert("hello,ajax!"); <BR>} <BR>window.hello(); <BR>//--> <br></script> <br> </div> <br>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: <br>var a=1; <br>alert(window.a); <br> will pop up a dialog box showing 1. The same principle applies to sharing variables and functions between different frameworks by calling them through the window object. <br>For example: a product browsing page consists of two sub-frames. The left side represents the link of 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 Add items to cart. <br>In this example, you can use the left navigation page to store the products that the user wants to buy, because when the user clicks the navigation link, what changes is another page, the product display page, while the navigation page itself remains unchanged. , so the JavaScript variables in it will not be lost and can be used to store global data. The implementation principle is as follows: <br><br>Assume that the left page is link.html and the right page is show.html. The page structure is as follows: <br><div class="codetitle"> <span><a style="CURSOR: pointer" data="72240" class="copybut" id="copybut72240" onclick="doCopy('code72240')"><u>Copy code</u></a></span> The code is as follows: </div> <div class="codebody" id="code72240"> <br><!DOCTYPE HTML PUBLIC "-//W3C//DTDHTML 4.0 Transitional//EN"> <br><html> <br><head> <br><title> New Document </title> <br></head> <br><frameset cols="20%,80%"> <br>< frame src="link.html"name="link" /> <br><frame src="show.html"name="show" /> <br></frameset> <br>< /html> <br> </div> <br>You can add a statement like this next to the products displayed in show.html: <br><a href="void(0)"onclick="self.parent.link. addToOrders(32068)">Add to shopping cart</a> <br>where link represents the navigation frame, the arrOrders array is defined in the link.html page to store the id of the product, and the function addToOrders() is used to respond to the product next to it [ For the click event of the purchase] link, the parameter id it receives represents the id of the product. In the example, it is a product with an id of 32068: <br><div class="codetitle"> <span><a style="CURSOR: pointer" data="54486" class="copybut" id="copybut54486" onclick="doCopy('code54486')"><u>Copy code </u></a></span> The code is as follows:</div> <div class="codebody" id="code54486"> <br><script language="JavaScript" type="text/javascript"> <br><!-- <BR>var arrOrders=new Array( ); <BR>function addToOrders(id){ <BR>arrOrders.push(id); <BR>} <BR>//--> <br></script> <br> </div> <br>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. <br>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. <br><br>The value of the control in the Iframe page that is referenced in this page can be written directly: <br><div class="codetitle"> <span><a style="CURSOR: pointer" data="81189" class="copybut" id="copybut81189" onclick="doCopy('code81189')"><u>Copy code</u></a></span> Code As follows: </div> <div class="codebody" id="code81189"> <br>function test() { <br>var num = window.iframename.inputtextname.value; <br>alert( num ); <br>} <br> </div> <br>When the Iframe in this page wants to call the js code in the page, you can directly write: <br><input value="click" type="button"onclick="window.parent.test()" />
