数组的map方法

map()对数组的每个元素进行一定操作（映射）后，会返回一个新的数组，map()不会对空数组进行检测。map()不会改变原数组

varoldArr = [{first_name:"Colin",last_name:"Toh"},{first_name:"Addy",last_name:"Osmani"},{first_name:"Yehuda",last_name:"Katz"}];

functiongetNewArr(){

  returnoldArr.map(function(item,index){

    item.full_name = [item.first_name,item.last_name].join(" ");

    returnitem;

  });

}

console.log(getNewArr());