'JavaScript DOM Programming Art' Reading Notes - A Brief History of JavaScript_Javascript Skills

JavaScript was developed in cooperation between Netscape and Sun. When JavaScript 1.0 was released, Netscape Navigator dominated the browser market. Microsoft released its own VBScript language when it launched IE3, and also released a version of JavaScript under the name JScript, quickly catching up with Netscape. Facing competition from Microsoft, Netscape and Sun worked with ECMA (European Computer Manufacturers Association) to standardize the JavaScript language, and the ECMAScript language emerged, which is another name for the same language.

DOM is a set of methods for abstracting and conceptualizing the content of documents. Netscape Navigator 4 was released in June 1997, and IE4 was released in October of the same year. Both browsers have made many improvements over their earlier versions, greatly expanding the DOM and greatly increasing the functionality that can be accomplished through JavaScript. And web designers have also begun to come into contact with a new term: DHTML (dynamic HTML).

DHTML is not a new technology, but a term that describes the combination of HTML, CSS and JavaScript technologies. Unfortunately, NN 4 and IE 4 browsers use two incompatible DOMs. This leads to a ridiculous situation: programmers must know which browser environment they will run in when writing DOM script codes, so in practice, many scripts have to be written twice, once for Netscape Navigator and another Once for IE. At the same time, programmers must also write some code to detect which browser is running on the client. DHTML opened up a new world full of opportunities, but those who wanted to enter it found it was a world full of misery. As a result, it didn't take long for the technology to be described as a "publicity stunt" and "difficult to implement."

While browser manufacturers are launching a marketing war using DOM as a weapon, W3C combines everyone’s strengths to launch a standardized DOM. It is gratifying that Netscape, Microsoft and other browser manufacturers were able to put aside their hostility to each other and work with the W3C to develop new standards, and completed the "Level 1 DOM" (DOM Level 1) in October 1998. 1).

W3C’s definition of DOM is: “An interface that is independent of system platform and programming language. Programs and scripts can dynamically access and modify the content, structure and style of documents through this interface.” The standardized DOM launched by W3C, in In many aspects, such as independence and scope of application, it far exceeds the various proprietary DOMs launched by browser manufacturers who are fighting each other.

Almost all browsers today have built-in support for DOM. We have witnessed an upsurge in learning DOM scripting triggered by asynchronous data transmission technology (Ajax). With the many new features of HTML5 DOM, how can we not make people think about the future of the Web?

The above is my summary of the first chapter of "JavaScript DOM Programming Technology" (2nd Edition), to understand the development history of JavaScript.