JavaScript: Abbreviation-js is a literal scripting language and one of the core technologies of the World Wide Web
One: What are the data types of js
JS data types are divided into two types: simple data types and complex data types
Simple data types: string, number, boolean, null, undefined, symbol, Bigint
Complex data types: object (function, array, object)
Two: data type characteristics
Simple data types: data stored directly on the stack
Complex data types: reference addresses are stored on the stack, and real data addresses are stored on the heap
Three: Data type detection method
typeof: Only basic data types can be detected --- the return value is a data type
instanceof: can only detect whether it is a reference data type --- the return value is true or false
constructor: basically can detect all data types except null and undefined
Object.prototype.toString.call: in call (data value is data type)
Array.isArray(): only used to detect whether it is an array