Question

我想找到两个数组之间的匹配值，并创建一个json数组，如果值匹配则设置为true，否则将设置为false。我知道，secondaryArray中的值将始终与第一个数组中的某些值匹配，并且将始终较小，因为secondArray是基于第一个数组创建的。

let firstArray = ["One", "Two", "Three", "Four", "Five"];
let secondArray = ["Three", "Four"];
let jsonArray = [];

我想创建一个json数组：

[
  {
    "name": "One",
    "matched": false
  },
  {
    "name": "Two",
    "matched": false
  },
  {
    "name": "Three",
    "matched": true
  },
  {
    "name": "Four",
    "matched": true
  },
  {
    "name": "Five",
    "matched": false
  }
]

通常，我会这样做：

            firstArray.forEach(firstElement=>{
              secondArray.forEach(secondElement=>{
                  if(firstArray.indexOf(secondElement)>=0){
                      jsonArray.push({'name': secondElement, 'matched': true});
                  }else{
                      jsonArray.push({'name': secondElement, 'matched': false});
                  }
              });
          });

但这只会创建一个具有重复值的json数组，其中名称相同，但是匹配的值是false和true。

似乎我迷失在一个非常简单的事情中。

Answer 1

这里所有其他解决方案都执行不必要的计算；它们的运行时间与数组长度的平方成正比。尝试使用大小为100k +的数组运行它们：-）

您要寻找的解决方案非常简单，并且可以在O(n)中运行：

let firstArray = ["One", "Two", "Three", "Four", "Five"];
let secondArray = ["Three", "Four"];

let map = {};
firstArray.forEach(i => map[i] = false);
secondArray.forEach(i => map[i] === false && (map[i] = true));
let jsonArray = Object.keys(map).map(k => ({ name: k, matched: map[k] }));

Answer 2

使用find检查元素是否存在

firstArray.forEach(secondElement=>{
  let exist = secondArray.find((item) => item === secondElement);
  if(exist){
    jsonArray.push({'name': secondElement, 'matched': true})
  }else{

    jsonArray.push({'name': secondElement, 'matched': false})
  }
});

Demo

Answer 3

尝试一下：

  let firstArray = ["One", "Two", "Three". "Four", "Five"];
  let secondArray = ["Three", "Four"];
  let jsonArray = [];
  firstArray.forEach(firstElement=>{
        if(secondArray.indexOf(firstElement)>=0){
            jsonArray.push({'name': firstElement, 'matched': true});
        }else{
            jsonArray.push({'name': firstElement, 'matched': false});
        }
 });

希望此代码对您有帮助

Answer 4

我们可以使用

Array.prototype.includes（）

检查数组中是否存在元素

let firstArray = ["One", "Two", "Three", "Four", "Five"];
let secondArray = ["Three", "Four"];
let jsonArray = [];

firstArray.forEach(val=>{

if(secondArray.includes(val))
{
  jsonArray.push({'name': val, 'matched': true})

}else{
  jsonArray.push({'name': val, 'matched': false})
}

})

console.log(jsonArray);

Answer 5

您可以结合使用map和includes助手来实现这一目标。

let firstArray = ["One", "Two", "Three", "Four", "Five"];
let secondArray = ["Three", "Four"];
let jsonArray = [];

jsonArray = firstArray.map(i => {
   return { 'name': i, 'matched': secondArray.includes(i) };
});

console.log(jsonArray);

Answer 6

您可以通过两种方式进行操作。

Way1:
let array1 = ['a','b','c','d'];
let array2 = ['b','d'];
let commonArray = [];

array1.forEach( x => {
    if(array2.indexOf(x) != -1){
      commonArray.push(x);
    }
});`

console.log(commonArray);   //commonArray is the resulting array

Way2: Use intersection of Underscore.js

At first you have to import underscore:  
import * as _ from 'underscore';`  

Then use intersection to calculate common.  
commonArray = _.intersection(array1, array2);

console.log(commonArray);   //commonArray is the resulting array

在两个数组中查找匹配值

6 个答案: