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Introduction to JavaScript: First Steps

Null & Undefined

Explore how JavaScript uses null and undefined to represent variables without values. Understand their differences and best practices for assigning these types to manage your code more clearly and effectively.

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There are two more variable types that we should discuss.

undefined

undefined is meant to represent the idea that something doesn’t exist. When we try to use a variable that has no value, we get undefined. Here’s an example.

Javascript (babel-node)
let variable;
console.log(variable); // -> undefined

When we declare a variable using let but don’t give it a value, it receives the default value of undefined. This is JavaScript telling us that we’re trying to use something that isn’t there.

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