What is js

The full name of js is javascript, which is an object- and event-driven scripting language with security performance.
Object-based: Three characteristics of object-oriented: encapsulation, inheritance, and polymorphism. Because there is no concept of inheritance in js, it means that new objects cannot be derived from the current objects. Without inheritance, there is no way to talk about polymorphism, so js is based on objects.
Event-driven: Refers to the actions made by the user to the browser. Generally, actions made through the mouse or keyboard are called events. Drive refers to the browser's response to an event.
Security performance: Refers to the operational safety, js does not have permission to access the operating system, which means that files and registry cannot be operated, so that viruses or Trojan horses cannot be created.
Script language: The script language can be executed without being compiled. js does not need to be compiled, it is directly interpreted and executed by the browser.