The Object hasOwnProperty() method

Find out all about the JavaScript hasOwnProperty() method of an object

Called on an object instance, accepts a string as argument. If the object has a property with the name contained in the string argument, it returns true. Otherwise it returns false.

Example:

const person = { name: 'Fred', age: 87 }
person.hasOwnProperty('name') //true
person.hasOwnProperty('job') //false