Q3：JS浅拷贝和深拷贝

浅拷贝

拷贝一层，深层次对象级别的只拷贝引用

Object.assign()

var obj1 = {
    a: "hello",
    b: {
        a: "hello",
        b: 21
    }
};
 
var cloneObj1 = Object.assign({}, obj1)
cloneObj1.a = "changed"
cloneObj1.b.a = "changed"
console.log(obj1.a)  //hello
console.log(obj1.b.a)

深拷贝

拷贝多层，每一层的数据都会被拷贝

序列化和反序列化

1 2	var obj1 = { body: { a: 10 } } var obj2 = JSON.parse(JSON.stringify(obj1))

Object.create()

function deepClone(initalObj, finalObj) {    
  var obj = finalObj || {}    
  for (var i in initalObj) {        
    var prop = initalObj[i]  // 避免相互引用对象导致死循环，如initalObj.a = initalObj的情况
    if(prop === obj) {            
      continue;
    }        
    if (typeof prop === 'object') {
      obj[i] = (prop.constructor === Array) ? [] : Object.create(prop)
    } else {
      obj[i] = prop
    }
  }    
  return obj
}