01JavaScript overview

1. Introduction to JavaScript

JavaScript is an interpreted programming language with object-oriented capabilities

It is a client-side scripting language based on object and event-driven and relatively safe, an interpreted programming language that runs on the client-side

Second, the role of JavaScript

Verify the data sent to the server, complete front-end and back-end interactions, and increase some logical implementations of user experience, etc.

The core of the front-end development is: JavaScript

Three, JavaScript features

Looseness

The variables in JS (JavaScript abbreviation JS) do not have a clear type, which is also called a weakly typed language (allowing a block of memory to be regarded as multiple types), that is, its variables do not have to have a clear type

Object attributes

Objects in JavaScript map property names to arbitrary property values

Inheritance mechanism

JS is based on prototypal inheritance

Four, JavaScript core

A complete JavaScript should consist of the following three parts:

Core (ECMAScript)
Document Object Model (DOM)
Browser Object Model (BOM)

Introduction to ECMAScript

ECMAScript is a scripting programming language standardized by Ecma International through ECMA-262

This language is widely used in the World Wide Web and is often called JavaScript or JScript, but in fact the latter two are implementations and extensions of the ECMA-262 standard.

Document Object Model (DOM)

Document Object Model (DOM, Document Object Model) is an application programming interface (API) for XML but extended to be applied to HTML. DOM has three levels, and each level will add many new content modules and standards.

Browser Object Model (BOM)

Browser Object Model (BOM, Browser Object Model) for accessing and operating the browser window

Developers can use the BOM to control the parts outside the browser display page