如何在JavaScript

Question

我得到了一个由数据库填充的二维数组：

var Index = [["value1_lang1", "value1_lang2", "value1_lang3", "3,6,11,"],["value1_lang1", "value1_lang2", "value1_lang3", "37,41,97,114,"],["value2_lang1", "value2_lang2", "value2_lang3", "9,14,33,"]];

该数组将获得超过600个值。我尝试使用以下两个for循环来完成它：

for(var i = 0; i < Index.length; i++) {
 for(var j = i + 1; j < Index.length; ) {
  var item1 = Index[i][0]; //Only have to compare the values from lang1
  var item2 = Index[j][0];

  if(item1 == item2) {
   var page1 = Index[i][3];
   var page2 = Index[j][3];

   if(page1 != page2) {
    var newpages = page1 + page2;
   } else {
    var newpages = page1;
   }

   Index[i][3] = newpages;
   Index.splice(j, 1);
   page1 = "";
   page2 = "";
   newpages = "";

  } else {
   j++;
  }
 }
}

结果应如下所示：

var Index = [["value1_lang1", "value1_lang2", "value1_lang3", "3,6,11,37,41,97,114"], ["value2_lang1", "value2_lang2", "value2_lang3", "9,14,33,"]];

但实际结果如下：

var Index = [[undefined, undefined, undefined, undefined],["value1_lang1", "value1_lang2", "value1_lang3", "3,6,11,37,41,97,114,"], ["value2_lang1", "value2_lang2", "value2_lang3", "9,14,33,"]];

Answer 1

根据我对要求的假设，以下应该适合你

＆＃13;

＆＃13;

var Index = [
  ["value1_lang1", "value1_lang2", "value1_lang3", "3,6,11"],
  ["value1_lang1", "value1_lang2", "value1_lang3", "37,41,97,114"],
  ["value2_lang1", "value2_lang2", "value2_lang3", "9,14,33"]
];

var map = {}; // Creating a map of unique values and value (will get updated)

for (var item of Index) {
  var val = map[item[0]];
  if (val) {
    val[3] = val[3] + item.slice(3).join(",");
  } else {
    val = item;
  }
  map[item[0]] = val;
}

var result = []; // Will be a collection of desired values
for (var key in map) {
  result.push(map[key]);
}

console.log(JSON.stringify(result));

＆＃13;

＆＃13;

＆＃13;

Answer 2

您可以使用内部数组的前三个元素作为哈希表的键并推送到结果集（如果不存在）或将元素附加到索引3处。

var data = [["value1_lang1", "value1_lang2", "value1_lang3", "3,6,11,"], ["value1_lang1", "value1_lang2", "value1_lang3", "37,41,97,114,"], ["value2_lang1", "value2_lang2", "value2_lang3", "9,14,33,"]],
    result = [];

data.forEach(function (a) {
    var key = a.slice(0, 3).join('|');
    if (!this[key]) {
        this[key] = a.slice();
        result.push(this[key]);
        return;
    }
    this[key][3] += a[3];
}, Object.create(null));

console.log(result);

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