对对象数组进行分组的最有效方法-JavaScript
假设我们有一个像这样的对象数组-
const arr = [
{ 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" }
];我们需要编写一个JavaScript函数，该函数接受一个这样的数组作为第一个参数。
我们的目的是能够基于多个或一个单独的属性（由第二个，第三个参数表示）对给定数组进行分组。
因此，如果我们进行groupby阶段，我们应该收到-
const output = [
{ Phase: "Phase 1", Value: 50 },
{ Phase: "Phase 2", Value: 130 }
];如果我们对阶段/步骤进行分组，我们应该收到-
const output = [
{ Phase: "Phase 1", Step: "Step 1", Value: 15 },
{ Phase: "Phase 1", Step: "Step 2", Value: 35 },
{ Phase: "Phase 2", Step: "Step 1", Value: 55 },
{ Phase: "Phase 2", Step: "Step 2", Value: 75 }
];示例
为此的代码将是-
const arr = [
{ 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" }
];
const groupBy = (array, groups, valueKey) => {
const map = new Map;
groups = [].concat(groups);
return array.reduce((acc, val) => {
groups.reduce((accu, value, ind, { length }) => {
let child;
if (accu.has(val[value])) {
return accu.get(val[value]);
};
if (ind + 1 === length) {
child = Object
.assign(...groups.map(value => ({ [value]: val[value]
})), { [valueKey]: 0 });
acc.push(child);
}
else {
child = new Map;
};
accu.set(val[value], child);
return child;
}, map)[valueKey] += +val[valueKey];
return acc;
}, []);
};
console.log(groupBy(arr, 'Phase', 'Value'));
console.log(groupBy(arr, ['Phase', 'Step'], 'Value'));输出结果
控制台中的输出将是-
[ { Phase: 'Phase 1', Value: 50 }, { Phase: 'Phase 2', Value: 130 } ]
[
{ Phase: 'Phase 1', Step: 'Step 1', Value: 15 },
{ Phase: 'Phase 1', Step: 'Step 2', Value: 35 },
{ Phase: 'Phase 2', Step: 'Step 1', Value: 55 },
{ Phase: 'Phase 2', Step: 'Step 2', Value: 75 }
]