Output: Add value if not exists Loop through the array to check whether a particular username value already exists and if it does do nothing, but if it doesn’t add a new object to the array. const arr = [{ id: 1, username: 'fred' }, { id: 2, username: 'bill' }, { ...
//code to check if a value exists in an array using javascript indexOf var fruits_arr = ['Apple', 'Mango', 'Grapes', 'Orange', 'Fig', 'Cherry']; var string = "Orange"; // Find in Array fruits_arr.indexOf('Tomato'); fruits_arr.indexOf('Grapes'); // Find in String string...
Example: const fruits = ["Banana", "Orange", "Apple", "Mango"]; fruits.includes("Mango"); check if an item exists in an array: const nums = [ 1, 3, 5, 7]; console.log(nums.includes(3)); // true
You can use the indexOf() method to check whether a given value or element exists in an array or not. The indexOf() method returns the index of the element inside the array if it is found, and returns -1 if it not found. Let's take a look at the following example:...
constarray=[3,8,12,6,10,2];// Find 10 in the given array.functioncheckForN(arr,n){for(leti=0;i<array.length;i++){if(n===array[i]){return`${true}${n}exists at index${i}`;}}return`${false}${n}does not exist in the given array.`;}checkForN(array,10); ...
constarray= [1,2,3,4]constindex =array.findIndex((num) => num >2)// 2constlastIndex =array.findLastIndex((num) => num >2)// 3 4.WeakMap支持使用Symbol作为key 很久以前,我们只能使用一个对象作为 WeakMap 的key。 constw...
constArraytoObj= (keys = [], values = []) => {if(keys.length===0|| values.length===0)return{};constlen = keys.length> values.length? values.length: keys.length;constobj = {};for(leti =0; i < len; ++i) { obj[keys[i]] = values[i]...
英文| https://javascript.plainenglish.io/6-amazing-and-useful-new-javascript-features-in-es13-b0719dfa0541 1. at 当我们想要获取数组的第 N 个元素时,我们通常使用 [] 来获取。 constarray= ['fatfish','medium','blog','fat','fish'] ...
console.log(array)// ['a', 'b', 'c']console.log(withArray)// ['a', 'fatfish', 'c'] 2.findLast 相信大家对 array.find 方法并不陌生,我们经常用它来查找符合条件的元素。 constarray= [1,2,3,4]consttargetEl =array.find((num) => num >2)// 3 ...
1.Array.prototype.includes() 用于判断数组是否包含指定值,如果是,则返回true;否则,返回假。 和之前indexOf的用法一样,可以认为是返回一个布尔值,语义上更加清晰。 代码语言:javascript 代码运行次数:0 运行 AI代码解释 constarr=[1,2,3,4,5];// Check if there is the number 3 in the arrayarr.include...