How Can I Get the Type Name of a JavaScript Object?

Get the Name of an Object's Type

In JavaScript, there is no direct equivalent to Java's class.getName() method for retrieving the name of an object's type. However, various approaches can be used for this purpose.

Using the Constructor Property

The constructor property of an object references its constructor function. For most objects, the constructor property will point to the constructor function used to create the object.

var myArray = [1, 2, 3];
myArray.constructor == Array; // true

However, this method has limitations:

• It may not work for objects created using multiple inheritance.
• It may not work across different window objects (e.g., in iframes).

Using the Instanceof Operator

The instanceof operator checks whether an object is an instance of a particular constructor function.

myArray instanceof Array; // true
myArray instanceof Object; // true

This method also has limitations:

• It does not work for literal values (e.g., numbers, strings).
• It may not work across different window objects.

Using the Name Property of the Constructor Property

Starting with IE9, the constructor.name property of an object can be used to retrieve the name of the constructor function.

myArray.constructor.name; // "Array"

However, this method is not reliable in earlier versions of Internet Explorer.

Using Object.prototype.toString

The Object.prototype.toString method returns a string representation of the object's type.

Object.prototype.toString.call('abc'); // "[object String]"
Object.prototype.toString.call(/abc/); // "[object RegExp]"
Object.prototype.toString.call([1, 2, 3]); // "[object Array]"

This method can be used to get the type name for all built-in types. However, it will return "Object" for all user-defined types.

Caution

It's important to note that the type of an object may change depending on how it is constructed. For example, if a function is defined anonymously, its constructor property will be assigned to Anonymous.

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