js怎么判斷一個(gè)數(shù)組對(duì)象里面有重復(fù)的值，并且刪除重復(fù)的值只保留一個(gè)比如 var arr = [{name:'a'},{name:'b'},{name:'c'},{name:'d'},{name:'a'}] 怎么對(duì)比