2 Quick Ways to Convert Values to Boolean in JavaScript 💻

The video version of this article. 📹

Every so often you will find a situation where you will want to convert values to booleans.

This is more usual these days where most linters stop == comparisons by default.

Just as a quick note 📝

In JavaScript, we have "truthy" values and "falsy" values. These are values that are considered true or false in the context of booleans.

Here are the falsy values

// 0, -0 "", 0.0, null, undefined, NaN

And for truthy, it's pretty much everything else including empty Array and Objects.

Let's show you the easy ways to convert:

const falsey = NaN;
const truthy = "truth";

Boolean(falsey); // returns false
Boolean(truthy); // returns true

We can use ! (not) operator to invert a value into it's inverted state. So !truthy === false. So if we invert it twice we get the original value a boolean.

const falsey = NaN;
const truthy = "truth";
// bang bang, problem solved! 🥳
!!falsey; // returns false
!!truthy; // returns true

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Written by Niall Maher

Founder of Codú - The web developer community! I've worked in nearly every corner of technology businesses; Lead Developer, Software Architect, Product Manager, CTO and now happily a Founder.


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