Javascript 数组中对象的总和

Sum values of objects in array

提问by chimichanga

I would like to create a sum of an array with multiple objects.

我想创建一个包含多个对象的数组的总和。

Here is an example: var array = [{"adults":2,"children":3},{"adults":2,"children":1}];

下面是一个例子： var array = [{"adults":2,"children":3},{"adults":2,"children":1}];

How do I return the sum of adults and the sum of children into a new variable for each?

如何将成人的总和和儿童的总和返回到每个的新变量中？

Thanks, c.

谢谢，C。

回答by Rayon

Use Array.prototype.reduce(), the reduce() method applies a function against an accumulator and each value of the array (from left-to-right) to reduce it to a single value.

使用Array.prototype.reduce()，reduce() 方法对累加器和数组的每个值（从左到右）应用一个函数以将其减少为单个值。

var array = [{
  "adults": 2,
  "children": 3
}, {
  "adults": 2,
  "children": 1
}];

var val = array.reduce(function(previousValue, currentValue) {
  return {
    adults: previousValue.adults + currentValue.adults,
    children: previousValue.children + currentValue.children
  }
});
console.log(val);

回答by DINESH Adhikari

 array = [{"adults":2,"children":3},{"adults":2,"children":1}];

 var totalChild = this.array.reduce((accum,item) => accum + item.children, 0)

 console.log(totalChild) //output 4

回答by Foxcode

Seeing nobody posted this yet... here is a nice shorthand method:

看到还没有人发布这个……这是一个很好的速记方法：

.reduce((acc, curr) => acc + curr.property, 0)

Example:

例子：

arr = [{x:1, y:-1}, {x:2, y:-2}, {x:3, y:-3}];

x_sum = arr.reduce((acc, curr) => acc + curr.x, 0); // 6
y_sum = arr.reduce((acc, curr) => acc + curr.y, 0); // -6

回答by ZigGreen

var array = [{"adults":2,"children":3},{"adults":2,"children":1}];
var sumProps = prop => (sum, obj) => sum += obj[prop];
var adultsCount = array.reduce( sumProps('adults'));
var childrenCount = array.reduce( sumProps('children'));

回答by Dawid Pura

We are not writing code for you, but I suppose you should try:

我们不是为您编写代码，但我想您应该尝试：

var val = array.reduce(function (sum, tuple) {
    return { adults: sum.adults + tuple.adults,
             children: sum.children + tuple.children };
});

回答by Nina Scholz

You can write a function for this task, which gets the array to iterate over an the property, which value should be added.

你可以为这个任务编写一个函数，它让数组迭代一个属性，应该添加哪个值。

The key feature of the function is the Array#reducemethode and a property which returns the actual count calue and the actual property value.

该函数的关键特性是Array#reduce方法和一个返回实际计数值和实际属性值的属性。

function count(array, key) {
    return array.reduce(function (r, a) {
        return r + a[key];
    }, 0);
}

var array = [{ "adults": 2, "children": 3 }, { "adults": 2, "children": 2 }],
    adults = count(array, 'adults'),
    children = count(array, 'children');

document.write('Adults: ' + adults + '<br>');
document.write('Children: ' + children + '<br>');

回答by RomanPerekhrest

To get a sum of each essence into separate variable:

要将每个本质的总和转化为单独的变量：

var array = [{"adults":2,"children":3},{"adults":2,"children":1}];
var adults_sum = 0, children_sum = 0;

array.forEach(function(obj){
    adults_sum += obj["adults"];
    children_sum += obj["children"];
});

console.log(adults_sum, children_sum); // 4 4

回答by worlf ee

May be it can help you and this also without use reduce func.

也许它可以帮助你，这也不需要使用reduce func。

var sumAdult=0;
var sumChildren=0;
var array = [{
  "adult": 2,
  "children": 3
}, {
  "adult": 2,
  "children": 1
}];
 function x(a,b){
   return a+b;
 }
for (y in array){  
  sumAdult=x(0, array[y].adult);
  console.log( "adult :" + sumAdult);
  sumChildren=x(0, array[y].children);
  console.log( "children :" + sumChildren);
}