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primitive-values.md

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What does 3 instanceof Number evaluate to? True or false? Explain your answer.

It will evaluate to false.

Let's look at this in depth:

var num1 = 3;
var num2 = new Number(3);

console.log(num1 instanceof Number); // false
console.log(3 instanceof Number); // false
console.log(num2 instanceof Number); // true

What's the difference between num1 and num2. In this case, num1 is a primitive or simple value. num2 is a complex value. Let's log the type of each variable.

console.log(typeof num1); // "number"
console.log(typeof num2); // "object"

So in the question, we use instanceof which is basically Constructor.prototype.isPrototype(value). The number 3 is a primitive value and therefore not a product of the Number constructor call.

For a deep dive on primitive types and reference types, I encourage you to read Angus Croll's The Secret Life of JavaScript Primitives.