基本数据类型
const a = 'malinshu'
const b = 'malinshu'
a === b // true
a==b //true
const num1 = 111
const num2 = 111
num1 == num2 // true
num1 === num2 // true
const b1 = true
const b2 = true
b1 == b2 // true
b1 === b2 // true
null === undefined //false
null == undefined //true
引用类型
const obj1 = {}
const obj2 = {}
obj1 === obj2 //false
obj1 == obj2 //false
const arr1 = [1, 2]
const arr2 = [1, 2]
arr1 === arr2 //false
arr1 == arr2 //false
const fun1 = () => {}
const fun2 = () => {}
fun1 == fun2 // false
fun1 === fun2 // false
总结：引用类型都不相等，基本数据类型除了null === undefined为false，其他为true
