Why can basic data types call methods in JS

problem

Why? string This basic data type can call methods , for example ‘a’.indexOf('a'), Isn't method invocation the ability of an object ？

answer

• JS In order to facilitate the operation of basic data types , Provides 3 Special reference types ：Boolean、Number、String, They have basic types of special behaviors
• actually , Whenever you read a basic type ,JS Internally, a basic wrapper type object is automatically created , Let's call some methods
• 'a'.indexOf('a') In the calling process, you will first let str = new String('a'), And then call indexOf, After calling, make str = null, Destroy the object .