[JS] Methods of Primitives

Introduction

Javascript enables us to use primitives (string, numbers, etc.) as objects and use methods with it. Primitives can’t use methods directly since they are not objects. Let’s take a look at how this works.

Solution

Here is an example.

let num = 123;

console.log(num.toString()); // 123 (type string)

1. num is a primitive number.
2. num is implicitly converted to a Number object when we call toString() method on num.
   • This is known as autoboxing or implicit type coercion.
   • JS automatically wraps the primitive value in its corresponding wrapper object to access the method.
3. The method runs and returns a new string (shown by console).
4. The object is destroyed, leaving the primitive num alone.

So, if we look at the whole process, it will look something like this.

let num = 123;
console.log(typeof num); // Output: "number"

let numObject = new Number(num);
console.log(typeof numObject); // Output: "object"

console.log(numObject.toString()); // Output: "123"

Conclusion

JavaScript primitive types work with temporary objects to use methods. JavaScript engines are well tuned to optimize that internally, so they are not expensive to call.