How to Check a Key Exists in JavaScript Object? Last Updated : 11 Jul, 2025 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 whether an object exists in javascript ? S 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 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 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 Check if a key exists inside a JSON object - JavaScript Below are some methods to check if a key exists inside a JSON object:1. Using hasOwnProperty() Method JavaScript hasOwnProperty() Method returns a boolean denoting whether the object has the defined property as its own property (as opposed to inheriting it). Syntaxobj.hasOwnProperty(prop);JavaScript 6 min read Check if a key exists inside a JSON object - JavaScript Below are some methods to check if a key exists inside a JSON object:1. Using hasOwnProperty() Method JavaScript hasOwnProperty() Method returns a boolean denoting whether the object has the defined property as its own property (as opposed to inheriting it). Syntaxobj.hasOwnProperty(prop);JavaScript 6 min read Check if a key exists inside a JSON object - JavaScript Below are some methods to check if a key exists inside a JSON object:1. Using hasOwnProperty() Method JavaScript hasOwnProperty() Method returns a boolean denoting whether the object has the defined property as its own property (as opposed to inheriting it). Syntaxobj.hasOwnProperty(prop);JavaScript 6 min read Like