本質(zhì)上是值傳遞和地址傳遞的區(qū)別
var arr = [1,2,3];
arr.forEach((item,index)=>{
item = 10; //不可改變數(shù)組arr的值--值傳遞
arr[index] = 10; //可改變數(shù)字arr的值--地址傳遞
});
var arr2 = [{id: 1},{id: 2}];
arr2.forEach((item)=> {
item.id = 3; //可改變arr2的值诗眨，對(duì)象屬于地址傳遞
});
