history

Origins: From simple input validation scripts to powerful programming languages

Development: Microsoft’s JScript clashed with Netscape’s JavaScript, advancing standardization. 1997 javasrip 1.1 proposal, undertaken by Ecma, produced the standard ECMAScript. Since then, all browsers use ECMAScript as the basis of their JS implementation.

ECMAScript

  • The ECMAScript standard belongs to JS. Specifically, JS also includes the DOM standard and BOM standard. But it is not private, and other languages can implement it. ECMAScript is a no-input/output (I/O) language that serves as a benchmark and requires a host environment to implement, which means not only Web browsers, but also Node.js and Adobe Flash (to be phased out).
  • Criteria: Seven aspects are described at the basic level. Syntax, types, statements, keywords, reserved words, operators, global objects.
  • Version: Version 6, commonly known as ES6, ES2015 or ES Harmony, is currently in its 10th edition until June 2019.
  • Conformance: refers to the conditions that need to be met in order to achieve the standard. Because the standard conditions are low, greatly improve the implementation of developers flexible line and authority, so widely praised.

Browser implementation

Five major browsers implement ES6 versions: Edge12+,Opera32+,Safari9+,Chrome49+, and Firefox45+

DOM

  • The DOM API that implements the DOM standard can add, delete, and change document nodes
  • Ecma drives the ECMAScript standard
  • W3C has promoted the DOM standard, and other languages have published their own DOM standard (THE SVG language), which enriches the DOM standard as a whole,

conclusion

JS: a scripting language used to interact with web pages, consisting of three parts, each browser to implement these three parts, to achieve the effect of the browser platform.

The implementation of BOM varies from platform to platform, so whether a browser implements JS depends on how well it implements ECMAScript and W3C standards.