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{"@context":"https://schema.org","@type":"FAQPage","mainEntity":[{"@type":"Question","name":"What is a constructor function in JavaScript?","acceptedAnswer":{"@type":"Answer","text":"A constructor function is a special function used to create and initialize objects. It is called with the new keyword, which creates a new object, binds this to it, and returns it automatically. By convention, constructor names start with a capital letter."}},{"@type":"Question","name":"What does the new keyword do in JavaScript?","acceptedAnswer":{"@type":"Answer","text":"The new keyword does four things: 1) Creates a new empty object, 2) Sets the prototype of the new object to the constructor function prototype, 3) Binds this to the new object inside the constructor, 4) Returns the new object (unless the constructor explicitly returns a different object)."}},{"@type":"Question","name":"What is the difference between constructor functions and factory functions?","acceptedAnswer":{"@type":"Answer","text":"Constructor functions use the new keyword and this to create objects, with methods typically on the prototype. Factory functions are regular functions that explicitly create and return objects, with methods on each instance. Factory functions offer more flexibility but use more memory for methods."}},{"@type":"Question","name":"Should I use constructor functions or ES6 classes?","acceptedAnswer":{"@type":"Answer","text":"ES6 classes are syntactic sugar over constructor functions and are preferred in modern JavaScript. They provide cleaner syntax, built-in inheritance with extends, and other features like static methods. Under the hood, classes still use prototypes."}},{"@type":"Question","name":"What happens if you forget the new keyword?","acceptedAnswer":{"@type":"Answer","text":"Without new, this refers to the global object (or undefined in strict mode), and properties are added to the wrong object. The function returns undefined instead of the new instance. Use strict mode or the new.target check to catch this error."}}]}