JavaScript Empty Values

Photo by Christopher Gower on Unsplash

What is an empty value?

Well, empty values are those values that are used to denote the absence of a meaningful value. They are themselves values, but without any information.

JavaScript has to empty values, null and undefined. Let’s explain each of them:


Null is a type of value to be used for new variables with an explicit value of null. But null is also a type of object, but this is a JavaScript bug, Null should be null. Let’s see some examples.

let emptyValue = null; //Binding
console.log(emptyValue) // output -> null
typeof null //output -> "object" //Javascript bug

Like you see, even JavaScript has bugs. Be careful using this value, because you can get unexpected behavior.


Undefined is a value assigned to every variable that don’t has been assigned any other value, for example:

let undefinedVariable; //declared, assigned as undefined by default
output // undefined
undefinedVariable = 4; // assigned, value changed to type Number
output// 4


Every time you are going to compare null with undefined you have to be careful about the automatic type conversion, because JavaScript will give you unexpected behavior, check out this:

console.log(null == undefined); //type conversion
output// true
console.log(null === undefined); //without type conversion
output// false

Take care and be patient with JavaScript, if you want to know more about it, check this out EloquentJavaScript.

Passionate reading || Coding Addicted || FullStack Web Developer from Costa Rica

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