js 实现浅拷贝的方式

浅拷贝，只能拷贝一层对象，针对对象的嵌套无法解决

1. array.slice

var numbers = [1,2,3]
var new_numbers = numbers.slice();

1. array.concat

var strings = ['a', 'b', 'c']
var new_strings = strings.concat();

1. Object.assign

var person = {name: 'garen', age: 18};
var new_person = Object.assign({}, person);

1. 展开运算符

var fruits = ['apple', 'banana', 'orange'];
var new_fruits = [...fruits];

1. 自己实现shadowCopy

function shadowCopy(target) {
    if(typeof target !== null && typeof target === 'object') {
      let cloneTarget = Array.isArray(target) ? []: {};
    for (let prop in target) {
      if(target.hasOwnProperty(prop)) {
          cloneTarget[prop] = target[prop] 
      }    
    }
    return cloneTarget;
  } else {
      return target;
  }
}