深拷贝

function deepClone (o) {
    if(typeof o !== 'object') return o
    let n
    if(Array.isArray(o)){
        n = new Array(o.length)
        o.forEach((v,i)=>{n[i] = deepClone(v)})
    } else {
        n = {}
        Object.keys(o).forEach((key)=>{n[key] = deepClone(o[key])})
    }
    return n
}

测试

const a = {
  a: [
    1,
    [4],
    {
      a: {
        c: [4]
      }
    }
  ]
}

const b = deepClone(a);

a.c = "c";
console.log(a);
console.log(b);
console.log(a.c);
console.log(b.c);