1.数组拼接的四种方法

   // apply()  把b拼接到a上
    let a = ['1', '2']
    let b = ['2', '3']
    a.push.apply(a, b)
    alert(a)

  // for循环拼接上去
    let a = ['1', '2']
    let b = ['2', '3']
    b.forEach(item => a.push(item))
    alert(a)

  // concat拼接 
    let a = ['1', '2']
    let b = ['2', '3']
    alert(a.concat(b))

  // ...扩展运算
    let a = ['1', '2']
    let b = ['2', '3']
    alert([...a, ...b])

2.对象合并的方法

  // Object.assign(target, ...sources) 该方法只会拷贝源对象自身的并且可枚举的属性到目标对象。
    var a = { a: 1}
    var b = { b: 2}
    console.log(Object.assign(a, b))

  // ...扩展运算符
    var a = { a: 1}
    var b = { b: 2}
    console.log({...a,...b})

  // 没看会
   ![image.png](https://p3-juejin.byteimg.com/tos-cn-i-k3u1fbpfcp/1a66ca01490146d0af22ea6252b778c3~tplv-k3u1fbpfcp-watermark.image)