Checking an Object let user = { name: 'John Doe', age: 17, profession: 'Farmer' }; // Check if key exists let hasKey = user.hasOwnProperty('name'); if (hasKey) { console.log('This key exists.'); } else { console.log('This key does not exist.'); } Checking an Array ...
put-array-or-string-here.indexOf() Code //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.in...
check if an item exists in an array: const nums = [ 1, 3, 5, 7]; console.log(nums.includes(3)); // true
// function return if an element is found in the array, else falsefunctioncheckTrueExistsArray(array) {for(vark=0;k<array.length;k++) {if(array[k]) {returntrue;break;}}returnfalse;}vararrayVariable=[false,false,true,false,true];vararrayVariable1=[false,false,false,false,false];console....
<script>varfruits=["Apple","Banana","Mango","Orange","Papaya"];// Check if a value exists in the fruits arrayif(fruits.indexOf("Mango")!==-1){alert("Value exists!")}else{alert("Value does not exists!")}</script> ES6 has introduced theincludes()method to perform this task very...
Understanding Undefined Variables in JavaScript Difference between Undefined and Null in JavaScript Common Scenarios for Undefined Variables 1. Uninitialized Variables 2. Function Parameters Not Provided 3. Accessing Non-Existing Object Properties 4. Array Indices Methods to check if a Variable is Undefine...
Vue.JS check if Array,Object or String is empty: In Vue.js, To check if an array is empty in Vue.js, you can use the Array.length property, which returns the number of elements in the array To check if the string is empty in Vue.js, you can use the
In JavaScript, you can check if a key exists in a JSON object in the following ways: Using Object.prototype.hasOwnProperty(); Using the in Operator; Checking Against undefined. Using Object.prototype.hasOwnProperty() You can use the Object.prototype.hasOwnProperty() method to check ...
You can check if a key exists in an object using the hasOwnProperty method or the in operator. Let's first take a look at the hasOwnProperty method. const user = { name: 'Jane', age: 30, city: "Auckland", country: "New Zealand" }; if (user.hasOwnProperty('city')) { console...
Here, we will see how to check if a given key exists as a key-value pair inside a JavaScript Object? We will first see how it is done and then see a practical use case where you need to check if a certain key exists in a JavaScript Object?