underscorejs groupby和filter

Question

我有一个对象数组。我想groupby＆amp; filter(remove)对象，未定义的类别。请参阅下面的脚本以获得更清晰：

arrayFlatten = [
      {
        area:"Digital",
        category:undefined,
        qId:"q11",
        qqId:"step1",
        type:"Reduce",
        val:1,
        userId:1,
        weightedAverage:0
      },
      {
        area:"Digital",
        category:"Analytics",
        qId:"q1",
        qqId:"step1",
        type:"Reduce",
        val:1,
        userId:1,
        weightedAverage:0
      },
      {
        area:"Digital",
        category:"Analytics",
        qId:"q1",
        qqId:"step2",
        type:"Reduce",
        val:1,
        userId:1,
        weightedAverage:0
      }
]

用于按

分组的命令

var groupCategory = _.groupBy(arrayFlatten,'category');
console.log(groupCategory);

预期结果应该如下：

arrayFlatten = [
          {
            area:"Digital",
            category:"Analytics",
            qId:"q1",
            qqId:"step1",
            type:"Reduce",
            val:1,
            userId:1,
            weightedAverage:0
          },
          {
            area:"Digital",
            category:"Analytics",
            qId:"q1",
            qqId:"step2",
            type:"Reduce",
            val:1,
            userId:1,
            weightedAverage:0
          }
    ]

Answer 1

filteredArray = _.filter(
    arrayFlatten,
    function (obj) {
        return obj.category !== undefined;
    }
);

filteredArray将包含没有未定义类别的数组。

您也可以使用此处所述的Array.filter()在大多数现代浏览器中不使用下划线执行此操作：https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/filter