Learn the pair and stack of js every day

var a={h1: '11'};
var b=a;
a=null;
console.log(a,b) //null {h1: "11"}

The reason for the above example: a=null just cancels the reference, but does not change the heap, and b still points to the original heap and still retains the old value.

var a = {n: 1};
var b = a;
a.x = a = {n: 2};    //   等价于  b.x = a = {n: 2};  
console.log(a);    //{n:2}
console.log(a.x);    //undefined
console.log(b);    //{n:1,x:{n:2}}
console.log(b.x);    //{n: 2}

The reason for the above example: the writing of a={n:2} changes the reference of a, but the reference of b remains unchanged;