SOURCE

let a = {b:1}, c = a;
console.log(a);// { b: 1 }
c.b = 2;
a = {b:3};
console.log(a);// { b: 3 }
console.log(c);// { b: 2 }

let x = new Map(), z = x;
x['y'] = '方括号表示法1';
x.set('y','set赋值1')
console.log(x.y);// 打印"方括号表示法1"
console.log(x.get('y')) // 打印"set赋值1"