2021-03-19地址面试题01

地址面试题

        let a = {
    name: '1' }
        let b = a
        a.x = a = {
    name: '2' }
        console.log(a.x) //undefined
        console.log(b.x)//{ name: "2" }

分析
首先

         a.x = a = {
    name: '2' }
         等于
          a.x = {
    name: "2" }
        a = {
    name: "2" };

所以

        let a = {
    name: '1' }
        let b = a  //复制a的内存地址  浅复制 a和b指向同一个内存地址
        // a.x = a = { name: '2' }
        //a和b指向同一个内存地址 a发生改变b也改变
        a.x = {
    name: "2" }
        //a被重新赋值 a内存地址改变  a和b不再指向同一个地址
        a = {
    name: "2" };
        console.log(a.x) //undefined  a中没有x属性
        console.log(b.x)//{name: "2"}