[JavaScript] -- Overview, javascript Overview

[JavaScript] -- Overview, javascript Overview
I. Overview

JavaScript is an object-oriented and interpreted programming language. That is to say, it is a client scripting language based on object and event-driven and with relative security. Because it does not need to run in a language environment, but only needs to support its browser. Its main purpose is to verify data sent to the server, increase Web interaction, and enhance user experience.

Ii. Features

1. Explanatory
JavaScript is a scripting language and a scripting language widely used for Web development on the client. It is often used to add dynamic functions to HTML webpages, such as responding to various operations of users.
2. Object-based language
JavaScript is an object-based programming language, but it is not a fully object-oriented language. Because there is no class concept, everything is derived from a copy of an existing object.
3. Dynamic
JavaScript is event-driven and can respond directly to user or customer input without going through web server programs. An event-driven operation is an operation performed on the home page.
4. cross-platform
JavaScript depends on the browser itself and has nothing to do with the operating environment. As long as the computer can run the browser and support the JavaScript browser, it can be correctly executed.
5. Security
As a security language, JavaScript is not allowed to access local hard disks, store data on servers, and modify or delete network documents, information Browsing or dynamic interaction can only be achieved through a browser. This effectively prevents data loss or illegal access to the system.

Iii. Knowledge Structure

JavaScript is divided into the following three parts: ECMAScript, BOM, and DOM.

ECMAScript:ECMAScript has no dependency with Web browsers. ECMAScript defines only the basis of this language, on which a more complete scripting language can be built. Our common Web browser is only one of the possible hosting environments implemented by ECMAScript. It consists of syntax, type, statement, keyword, reserved word, operator, and object.

BOM (Brower Object Model ):It provides many objects for accessing the browser. However, BOM itself has no standards. The core object of BOM is window.

DOM (Document Object Model ):APIS for HTML and XML documents (application interfaces ). DOM depicts a hierarchical node tree that allows developers to add, remove, and modify a part of a page. It has become a true cross-platform and language-neutral way of displaying and operating page tags.

JS is an essential knowledge for front-end development. JavaScript is indispensable for future course learning and project implementation. Subsequent learning is based on JS. We must master the content of each part carefully.