我有以下JSON数组，我想创建对象表单状态键计数
[ { "id": "65:0", "status": "ORANGE" }, { "id": "65:0", "status": "GREEN" }, { "id": "65:0", "status": "ORANGE" }, { "id": "65:0", "status": "YELLOW" }, { "id": "65:0", "status": "RED" }, { "id": "65:0", "status": "GREEN" }, { "id": "65:0", "status": "GREEN" }, { "id": "65:0", "status": "ORANGE" }, { "id": "65:0", "status": "YELLOW" }, { "id": "65:0", "status": "GREEN" } ]
要计算状态键值并创建以下对象
{ 'ORANGE' : 3, 'GREEN' : 4, 'YELLOW' : 2, 'RED' : 1, }
使用 Array#reduce 方法
Array#reduce
var res = data.reduce(function(obj, v) { // increment or set the property // `(obj[v.status] || 0)` returns the property value if defined // or 0 ( since `undefined` is a falsy value obj[v.status] = (obj[v.status] || 0) + 1; // return the updated object return obj; // set the initial value as an object }, {}) var data = [{ "id": "65:0", "status": "ORANGE" }, { "id": "65:0", "status": "GREEN" }, { "id": "65:0", "status": "ORANGE" }, { "id": "65:0", "status": "YELLOW" }, { "id": "65:0", "status": "RED" }, { "id": "65:0", "status": "GREEN" }, { "id": "65:0", "status": "GREEN" }, { "id": "65:0", "status": "ORANGE" }, { "id": "65:0", "status": "YELLOW" }, { "id": "65:0", "status": "GREEN" }]; var res = data.reduce(function(obj, v) { obj[v.status] = (obj[v.status] || 0) + 1; return obj; }, {}) console.log(res);
虽然可以使用 Array#forEach 具有相同代码的方法。
Array#forEach
var res = {}; data.forEach(function(v) { res[v.status] = (res[v.status] || 0) + 1; }) var data = [{ "id": "65:0", "status": "ORANGE" }, { "id": "65:0", "status": "GREEN" }, { "id": "65:0", "status": "ORANGE" }, { "id": "65:0", "status": "YELLOW" }, { "id": "65:0", "status": "RED" }, { "id": "65:0", "status": "GREEN" }, { "id": "65:0", "status": "GREEN" }, { "id": "65:0", "status": "ORANGE" }, { "id": "65:0", "status": "YELLOW" }, { "id": "65:0", "status": "GREEN" }]; var res = {}; data.forEach(function(v) { res[v.status] = (res[v.status] || 0) + 1; }) console.log(res);
