JavaScript 数组排序通过对相同元素求和

Question

尝试在 JavaScript 中对数组项进行排序和分组时，我遇到了一些麻烦。这是示例输入:

var arr = [
{merchantName: '', branchName: 'e', branchAddress: '', total: 10.5},
];

我想要实现的输出:

var arr = [
{merchantName: '', branchName: '', branchAddress: '', total: 10.5},
];

我想按 branchName 对它进行排序，例如对相同的 branchName 求和，然后同时绑定(bind)所有其他属性，例如 merchantName 和 branchAddress 连在一起，这样我就可以像这样访问它们:

for(var i = 0; i < arr.length; i++){
            console.log(arr[i].merchantName + ' ' + arr[i].branchName + ' ' + arr[i].branchAddress + ' ' + arr[i].total);
        }

我什至不知道如何开始它。有什么想法可以实现吗？

Answer 1

下面是我的做法:

1. 根据 branchName 属性将数组分组到 hashmap - 计算总数。

2. 从hashmap中取出数组并排序

请看下面的演示:

var arr = [
{merchantName: 'Giant', branchName: 'Giant Marine', branchAddress: 'Terrace 56 Branch Blk 56 Marine Terrace #01-259/261 Singapore 440056', total: 10.5},
{merchantName: 'Ntuc', branchName: 'Ntuc Zhongshan Mall Branch', branchAddress: ' Zhongshan Mall Balestier #02-01, 20 Ah Hood Road, 329984', total: 12.149999999999999},
{merchantName: 'Giant', branchName: 'Giant Kim Keat 260 Branch', branchAddress: ' Blk 260 Kim Keat Avenue #01-01 Singapore 310260', total: 5.1},
{merchantName: 'Ntuc', branchName: 'Ntuc Scotts Square Branch', branchAddress: ' Scotts Square #B1-03 To 07 & #B1-10, 6 Scotts Road, 228209', total: 4},
{merchantName: 'Ntuc', branchName: 'Ntuc Zhongshan Mall Branch', branchAddress: ' Zhongshan Mall Balestier #02-01, 20 Ah Hood Road, 329984', total: 4},
{merchantName: 'Ntuc', branchName: 'Ntuc Zhongshan Mall Branch', branchAddress: ' Zhongshan Mall Balestier #02-01, 20 Ah Hood Road, 329984', total: 8}
];

// create a hashmap
var hash = arr.reduce(function(p,c){
  if(!p[c.branchName])
    p[c.branchName] = c;
  else
    p[c.branchName].total += c.total;
  return p;
}, Object.create(null))

// now extract the result and sort them
var result = Object.keys(hash).map(function(e){
   return hash[e];
}).sort(function(a,b){
   return a.branchName - b.branchName;
});

console.log(result);

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