Question

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

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},
];

我想通过branchName对其进行排序，例如总结同一branchName的总数，然后同时绑定所有其他属性，如merchantName和branchAddress，以便我可以像以下一样访问它们：

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

我实际上根本不知道如何开始它。任何想法如何实现它？

先谢谢！

Answer 1

所以我会这样做：

根据hashmap属性将数组分组为branchName - 计算总数以及此值。
从hashmap取出数组并对其进行排序

见下面的演示：

＆＃13;

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);

＆＃13;

.as-console-wrapper{top:0;max-height:100%!important;}

＆＃13;

Answer 2

使用reduce()

的解决方案

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
  }
];

var newArr = arr.reduce(function(items, item) {

  var existing = items.find(function(i) {
    return i.branchName === item.branchName;
  });
  
  if (existing) {
    existing.total += item.total;
  } else {
    items.push(item);
  }
  
  return items;
}, []);

console.log(newArr);

Answer 3

看起来你想要做两件事：按branchName排序，然后为每个branchName输出一个值（重复结果/ group-by branchName）。

有几个潜在的问题。 1）上面显示的示例输出未按branchName排序，即使您声明a）您希望它按branchName排序，并且b）这将是一个示例。其次，输出并不完全是确定性的 - 特别是它似乎只输出第一个匹配的记录形式branchName，因此总属性的值 - 在同一branchName的记录之间变化 - 是显示的。所以...假设你A）想要对结果进行排序，并且B）不关心＆＃34;总和＆＃34;的价值。属性，这可以通过以下方式轻松完成：

I）对数组进行排序。有关示例，请参阅https://gist.github.com/umidjons/9614157：只需编写一个比较branchName值的比较函数。和， II）遍历结果，只要在branchName从前一个值改变时输出第一个记录。

通过总结相同的元素进行JavaScript数组排序

3 个答案: