JavaScript |未定义的索引[重复]

Posted 2023-02-27

【中文标题】JavaScript |未定义的索引[重复]

【英文标题】：JavaScript | undifined index [duplicate]

【发布时间】：2021-03-02 09:37:12

【问题描述】：

我卡了一段时间，不知道如何修复此代码。任何帮助表示赞赏

let firstArray = ["oranges", "milk", "eggs", "chocolate"]; // First Array
let secondArray = ["milk", "popcorn", "chocolate", "ham"]; // Second Array

let newArray = []; // New Array that will hold the values that are NOT in other array
debugger;
for(let i = 0; i < firstArray.length; i++) 
    for(let j = 0; j < secondArray.length; j++)
        if(firstArray[i] !== secondArray[j]) 
            newArray.push(newArray[i]);  // If oranges != milk > add new item > newArray = ['oranges']
        else if(firstArray[i] !== secondArray[j])
            newArray.push(newArray[j]);  // If milk != oranges > add new item > newArray = ['oranges']
        
    


console.log(newArray); // Print the new array

【参考方案1】：

看看includes()函数here。

let firstArray = ["oranges", "milk", "eggs", "chocolate"]; // First Array
let secondArray = ["milk", "popcorn", "chocolate", "ham"]; 
let newArray=[];
for(let i = 0; i < firstArray.length; i++) 
    if(!secondArray.includes(firstArray[i])) 
    newArray.push(firstArray[i]);
       

console.log(newArray);