js实现groupBy

先贴代码

function groupBy(list,key){
    return list.reduce((rv,current)=>{
        (rv[current[key]]=rv[current[key]]||[]).push(current)
        return rv
    },{})
}

举例

let list=[ 
    { Phase: "Phase 1", Step: "Step 1", Task: "Task 1", Value: "5" },
    { Phase: "Phase 1", Step: "Step 1", Task: "Task 2", Value: "10" },
    { Phase: "Phase 1", Step: "Step 2", Task: "Task 1", Value: "15" },
    { Phase: "Phase 1", Step: "Step 2", Task: "Task 2", Value: "20" },
    { Phase: "Phase 2", Step: "Step 1", Task: "Task 1", Value: "25" },
    { Phase: "Phase 2", Step: "Step 1", Task: "Task 2", Value: "30" },
    { Phase: "Phase 2", Step: "Step 2", Task: "Task 1", Value: "35" },
    { Phase: "Phase 2", Step: "Step 2", Task: "Task 2", Value: "40" }
]
groupBy(list,'Phase')

返回结果

{
    "Phase 1": [
        {
            "Phase": "Phase 1",
            "Step": "Step 1",
            "Task": "Task 1",
            "Value": "5"
        },
        {
            "Phase": "Phase 1",
            "Step": "Step 1",
            "Task": "Task 2",
            "Value": "10"
        },
        {
            "Phase": "Phase 1",
            "Step": "Step 2",
            "Task": "Task 1",
            "Value": "15"
        },
        {
            "Phase": "Phase 1",
            "Step": "Step 2",
            "Task": "Task 2",
            "Value": "20"
        }
    ],
    "Phase 2": [
        {
            "Phase": "Phase 2",
            "Step": "Step 1",
            "Task": "Task 1",
            "Value": "25"
        },
        {
            "Phase": "Phase 2",
            "Step": "Step 1",
            "Task": "Task 2",
            "Value": "30"
        },
        {
            "Phase": "Phase 2",
            "Step": "Step 2",
            "Task": "Task 1",
            "Value": "35"
        },
        {
            "Phase": "Phase 2",
            "Step": "Step 2",
            "Task": "Task 2",
            "Value": "40"
        }
    ]
}