查找两个数组具有相同值的索引答案

【问题标题】：Find Index where Two Arrays have same Value查找两个数组具有相同值的索引
【发布时间】：2021-02-19 01:52:45
【问题描述】：

如果我有两个数组，在 Javascript 中：

let arr1 = ["Dog", "Cat", "Monkey", "Zebra", "Goat", "Goose"];
let arr2 = ["Zebra", "Goat"];

如何找到匹配的较大数组的索引并将它们存储在另一个数组中，因此示例输出为：

let indexes = [3,4]

【问题讨论】：

标签： javascript arrays

【解决方案1】：

您可以使用Array.map 和Array.findIndex 实现预期输出

let arr1 = ["Dog", "Cat", "Monkey", "Zebra", "Goat", "Goose"];
let arr2 = ["Zebra", "Goat"];

const findIndexes = (param1, param2) => {
  let arr1 = [...param1];
  let arr2 = [...param2];
  //swap the arrays if the no.of array elements 
  //in the second array are greater than first
  if(arr1.length < arr2.length) {
    [arr1, arr2] = [arr2, arr1];
  }
  //Loop through all the items of the smaller array
  //check if the element is present in the bigger array
  return arr2.map(a2 => arr1.findIndex(a1 => a1 === a2));
}

console.log(findIndexes(arr1, arr2));

//here for "test", we'll get index as -1, because
//if the matching element is not found, findIndex will 
//return -1
let arr3 = ["Cat", "Goose", "test"];
console.log(findIndexes(arr3, arr1));

如果您希望获取找到的元素的索引并希望过滤掉所有-1s，下面是相同的代码。

let arr1 = ["Dog", "Cat", "Monkey", "Zebra", "Goat", "Goose"];
let arr2 = ["Zebra", "Goat"];

const findIndexes = (param1, param2) => {
  let arr1 = [...param1];
  let arr2 = [...param2];
  if(arr1.length < arr2.length) {
    [arr1, arr2] = [arr2, arr1];
  }
  return arr2.map(a2 => arr1.findIndex(a1 => a1 === a2)).filter(ele => ele !== -1);
}

console.log(findIndexes(arr1, arr2));

let arr3 = ["Cat", "Goose", "test"];
console.log(findIndexes(arr3, arr1));

【讨论】：

这很好——但它不能处理缺失的元素。我想过滤掉-1？
@akaphenom，我故意没有删除缺失元素的 -1。如果相应的元素不存在，那么许多 -1 将出现在输出中。

【解决方案2】：

let arr1 = ["Dog", "Cat", "Monkey", "Zebra", "Goat", "Goose"];
let arr2 = ["Zebra", "Goat"];
let indexes = []

arr1.forEach((item, index) => {
  if(arr2.includes(item)){
    indexes.push(index)
  }
})

console.log(indexes)

【讨论】：

【解决方案3】：

您可以通过映射您的搜索团队 (arr2) 然后在源数组 (arr1) 上使用 findIndex 方法来做到这一点，如下所示：

let arr1 = ["Dog", "Cat", "Monkey", "Zebra", "Goat", "Goose"];
let arr2 = ["Zebra", "Goat"];

const result = arr2.map(searchTerm => arr1.findIndex((compareTerm) => compareTerm === searchTerm));

console.log(result);

【讨论】：