JavaScript from entry to essence (1)-JavaScript Introduction

In today's society, professional practitioners and practitioners in other industries have heard JavaScript more or less. It is well known. However, JavaScript is far from anyone who uses it. In the current BS development, JS is an indispensable skill. Now let me know about JavaScript.

[What is JavaScript]
JavaScript is a cross-platform dynamic web page development scripting language based on Object and Event-Driven and with secure performance. Thanks to its strong compatibility, it has become a hot and essential development skill in BS development.

[Past and present of JavaScript]
The predecessor of JavaScript is LiveScript, a scripting language developed by Netscape. After Sun launched Java, Sun cooperated with Sun to launch JavaScript. There is also a small story here. When Netscape is working with Sun to redesign, the Java language has been very popular. So after the re-design of LiveScript is complete, before the release, with the help of the trendy word Java, it was renamed as JavaScript, and soon turned into a spread. After several updates, it became the javaScript currently used.
[JavaScript language features]
According to the definition of JavaScript, We can almost see what features it has.
1. JavaScript is a scripting language.
JavaScript is a scripting language. It uses a small program segment programming method and is embedded into a webpage. It is combined with HTML identifiers. In addition, JavaScript is an explanatory language that does not require pre-compilation. During execution, it is interpreted and executed line by line.

2. Object-based language.
JavaScript is based on objects rather than object-oriented languages. It is mainly because JavaScript does not provide abstract, inheritance, overloading, and other common functions of object-oriented languages. There is no concept of inheritance, and there is no concept of polymorphism, but in fact, each JavaScript Object is an instance of the same base class. It can use predefined objects or self-created objects. Therefore, its function comes from the interaction between methods of objects and scripts in the script environment.

3. simplicity.
JavaScript is a descriptive scripting language that is directly embedded into HTML and a simple and compact scripting language based on java basic statements and control flow.
Weak types are used in variable definition, without strict type restrictions in other languages.
In terms of operation, there is no need for high-performance machines or server channels, as long as there is a word processing software and a browser to run.

4. Dynamic.
JavaScript is dynamic and event-driven. Some local functions can be completed without the need of web server programs, such as verifying the validity of input. Program the event. After the event is triggered, the program segment is compiled.

5. cross-platform.
JavaScript is a scripting language. It depends on the browser itself and has nothing to do with the operating system. So as long as the browser supports JavaScript, it can run. Currently, mainstream browsers support JavaScript, so we don't have to worry about it.