javascript - 在 JavaScript 数组中求和

Question

我有一个正在我的页面上创建的动态 JavaScript 数组(这些数字都不会相同，有很多变化)，例如:

 myArray[ 1 ] = [295518, 2];
 myArray[ 2 ] = [123518, 123];
 myArray[ 3 ] = [295518, 43];
 myArray[ 4 ] = [295518, 65];
 myArray[ 5 ] = [234518, 3];
 myArray[ 6 ] = [567518, 56];

该数组的解释:

                [id number, quantity]
 myArray[ 1 ] = [295518,    2];

我需要将所有类似的 id 数组元素分组在一起并对它们的值求和。

 For instance: 295518 would add 2 + 43 + 65 = 110

然后我需要它用值更新页面上的 id:

 $("#295518").text(110); 

所以我的想法是这样的，但我不知道如何用 JavaScript 编写它:

 [start JavaScript loop]
      [grab distinct ids]
           [start id loop]
                [grab all values based on id]
                [sum their qty values]
                [set the id element on the page with the sum value]
                     [example: $("#295518").text(110); ]
           [end id loop]
 [/end JavaScript loop]

Answer 1

这应该可以解决问题:

var myArray = [
  [295518, 2],
  [123518, 123],
  [295518, 43],
  [295518, 65],
  [234518, 3],
  [567518, 56]
]

var result = {};

for (var i in myArray) {
  var key = myArray[i][0];
  var value = myArray[i][1];
  if (result[key]) {
    result[key] += value;
  } else {
    result[key] = value;
  }
}

console.log(result);

这与 jQuery 是一样的:

var myArray = [];
myArray.push([295518, 2]);
myArray.push([123518, 123]);
myArray.push([295518, 43]);
myArray.push([295518, 65]);
myArray.push([234518, 3]);
myArray.push([567518, 56]);

var result = {};

$(myArray).each(function() {
  var key = this[0];
  var value = this[1];
  if (result[key]) {
    result[key] += value;
  } else {
    result[key] = value;
  }
});

console.log(result);

<script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.3.1/jquery.min.js"></script>

<强> Here's a working example...