js中数组对象去重的几种方法

var arr = [{
   key: '01',
   value: '乐乐'
  }, {
   key: '02',
   value: '博博'
  }, {
   key: '03',
   value: '淘淘'
  },{
   key: '04',
   value: '哈哈'
  },{
   key: '01',
   value: '乐乐'
  }];
  // 方法1：利用对象访问属性的方法，判断对象中是否存在key
  var result = [];
  var obj = {};
  for(var i =0; i<arr.length; i++){
   if(!obj[arr[i].key]){
     result.push(arr[i]);
     obj[arr[i].key] = true;
   }
  }
  console.log(result); // [{key: "01", value: "乐乐"},{key: "02", value: "博博"},{key: "03", value: "淘淘"},{key: "04", value: "哈哈"}]
  // 方法2：利用reduce方法遍历数组,reduce第一个参数是遍历需要执行的函数，第二个参数是item的初始值
  var obj = {};
  arr = arr.reduce(function(item, next) {
   obj[next.key] ? '' : obj[next.key] = true && item.push(next);
   return item;
  }, []);
  console.log(arr); // [{key: "01", value: "乐乐"},{key: "02", value: "博博"},{key: "03", value: "淘淘"},{key: "04", value: "哈哈"}]

function deteleObject(obj) {
    var uniques = [];
    var stringify = {};
    for (var i = 0; i < obj.length; i++) {
        var keys = Object.keys(obj[i]);
        keys.sort(function(a, b) {
            return (Number(a) - Number(b));
        });
        var str = '';
        for (var j = 0; j < keys.length; j++) {
            str += JSON.stringify(keys[j]);
            str += JSON.stringify(obj[i][keys[j]]);
        }
        if (!stringify.hasOwnProperty(str)) {
            uniques.push(obj[i]);
            stringify[str] = true;
        }
    }
    uniques = uniques;
    return uniques;
}