How Can You Determine the Class of an Object in JavaScript?

Understanding JavaScript's Dynamic Nature: Determining Object Classes

In contrast to languages like Java, JavaScript lacks a direct equivalent to Java's .getClass() method due to its unique prototype-based design. However, there are various techniques to fulfill similar functionality.

Options for Determining Object Classes in JavaScript:

• typeof: Returns the data type (e.g., "object", "function") of a variable.
• instanceof: Tests if an object belongs to a specific class or is descended from it.
• obj.constructor: Points to the constructor function that created the object.
• func.prototype, proto.isPrototypeOf: Allows inheritance verification by checking if a prototype is an object's prototype.

Examples:

function Foo() {}
var foo = new Foo();

typeof Foo; // == "function"
typeof foo; // == "object"

foo instanceof Foo; // == true
foo.constructor.name; // == "Foo"
Foo.name // == "Foo"

Foo.prototype.isPrototypeOf(foo); // == true

Foo.prototype.bar = function (x) {return x+x;};
foo.bar(21); // == 42

Note: Minification tools like Uglify can modify class names. To prevent this in build tools like Gulp or Grunt, set the --mangle parameter to false.

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