How to Check a Key Exists in JavaScript Object? Last Updated : 21 Nov, 2024 Comments Improve Suggest changes Like Article Like Report Here are different ways to check a key exists in an object in JavaScript.Note: Objects in JavaScript are non-primitive data types that hold an unordered collection of key-value pairs. check a key exists in JavaScript object1. Using in Operator The in operator in JavaScript checks if a key exists in an object by returning a boolean value. It verifies if the specified property is present within the object, simplifying key existence validation.Syntax'key' in object JavaScript let exampleObj = { id: 1, remarks: 'Good' } // Check for the keys let output1 = 'name' in exampleObj; let output2 = 'remarks' in exampleObj; console.log(output1); console.log(output2); Outputfalse true 2. Using hasOwnProperty() MethodThe hasOwnProperty() method returns a boolean value that indicates whether the object has the specified property. The required key name could be passed in this function to check if it exists in the object. Syntaxobject.hasOwnProperty('key') JavaScript let exampleObj = { id: 1, remarks: 'Good' } // Check for the keys let output1 = exampleObj.hasOwnProperty('name'); let output2 = exampleObj.hasOwnProperty('remarks'); console.log(output1); console.log(output2); Outputfalse true 3. Using the Object.keys() MethodThe Object.keys() method in JavaScript retrieves an array of the object's keys. By checking if the desired key is included in this array, one can determine if it exists in the object.SyntaxObject.keys(obj); JavaScript const obj = { name: 'Sandeep', age: '32' }; if (Object.keys(obj).includes('age')) { console.log('true'); } else { console.log('false'); } Outputtrue Comment More infoAdvertise with us Next Article How to Check a Key Exists in JavaScript Object? sayantanm19 Follow Improve Article Tags : JavaScript Web Technologies JavaScript-Questions Similar Reads How to check whether an object exists in javascript ? Checking whether an object exists in JavaScript refers to determining if a variable or property has been declared and contains a valid value. This helps avoid errors when accessing or manipulating objects that may be undefined, null, or not initialized properly.Here we have some common approaches to 3 min read JavaScript Check if a key exists inside a JSON object When working with JSON objects in JavaScript, it's often necessary to check if a specific key exists within the object. This check is important, especially when dealing with dynamic or external data, to ensure that your code handles objects correctly and only accesses keys that are present. Below ar 3 min read How to Check an Object is Empty using JavaScript? These are the following ways that can be used to Check an Object is Empty using JavaScript: 1. Using Object.keys() Method - Mostly usedThe Object.keys() method returns an array that contains the property names of an object. If the length of array is 0, then object is empty.JavaScriptlet obj = {}; if 2 min read How to check a JavaScript Object is a DOM Object ? Checking if a JavaScript object is a DOM object involves verifying whether the object represents an element or component within the Document Object Model (DOM) of an HTML or XML document. This can be done by checking if the object is an instance of Node, Element, or other specific DOM interfaces.Wha 2 min read How to check if a value is object-like in JavaScript ? In JavaScript, objects are a collection of related data. It is also a container for name-value pairs. In JavaScript, we can check the type of value in many ways. Basically, we check if a value is object-like using typeof, instanceof, constructor, and Object.prototype.toString.call(k). All of the ope 4 min read Like