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This article mainly introduces the Javascript built-in variables top and parent have what different related knowledge, the content is detailed and easy to understand, simple and fast operation, has a certain reference value, I believe you read this Javascript built-in variables top and parent what different articles will have a harvest, let's take a look at it.

Top:

This change always refers to the browser window at the highest level of the split window. If you plan to execute the command at the highest level of the split window, you can use the top variable.

Parent:

This variable refers to the parent window that contains the current split window. If there is a split window within a window, and one of the split windows contains a split window, the split window at the second level can refer to the parent split window that contains it with the parent variable.

Attached: hierarchical relationship of Windwo object, Parent object, Frame object, Document object and Form object

Windwo object → Parent object → Frame object → Document object → Form object, as follows:

Parent.frame1.document.forms [0] .elements [0] .value

What are the characteristics of JavaScript 1. Js belongs to an interpretive scripting language

2. With the support of most browsers, js can run on multiple platforms and has cross-platform features.

3. Js is a weakly typed scripting language, which has no strict requirements on the data types used. It can convert types, which is simple and easy to use.

4. Js language is highly secure and can only browse information or interact dynamically through a browser, so as to effectively prevent data loss.

5. Object-based scripting language, js can not only create objects, but also use existing objects.

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