拥有一个对象数组,我想通过组合不同的键集来对值进行求和。更具体地说,有一组对象,描述膳食(0 - 早餐,1 - 小吃...),我想得出两个不同的总和:
- 每餐的营养值(value)(数量)总和
- 汇总全天的营养值(value)(数量)
对象数组示例如下:
var arrayIngredients = [{mealNumber: 4, name: "Sugars, total", quantity: 1.4300000000000002}, {mealNumber: 4, name: "Magnesium, Mg", quantity: 14.950000000000001}, {mealNumber: 3, name: "Vitamin A, IU", quantity: 27.9}]
有谁知道对给定键(名称)或多个键(mealNumber、名称)的值求和的最有效方法是什么?
最佳答案
您需要使用Array.prototype.reduce
(不需要第三方库)。
运行以下代码片段以获得详细示例:
var arrayIngredients = [{
mealNumber: 4,
name: "Sugars, total",
quantity: 1.4300000000000002
}, {
mealNumber: 4,
name: "Magnesium, Mg",
quantity: 14.950000000000001
}, {
mealNumber: 3,
name: "Vitamin A, IU",
quantity: 27.9
}];
var dayTotals = arrayIngredients.reduce(function(result, next) {
if (!result.hasOwnProperty(next.name))
result[next.name] = {
totalQuantity: 0
};
result[next.name].totalQuantity += next.quantity;
return result;
}, {}); // this empty object is injected as "result" argument
// in the Array.prototype.reduce callback #1 parameter
document.getElementById("result").textContent = JSON.stringify(dayTotals);
<div id="result"></div>
关于javascript - 如何通过任意一组键对数组元素进行分组?,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/31994129/