JavaScript Nullish Coalescing
An introduction to this feature of JavaScript: nullish coalescing
A powerful operator available in JavaScript is the nullish coalescing operator: ??
.
Have you ever used ||
to set a default value if a variable was null or undefined?
For example, like this:
const myColor = color || 'red'
Well, nullish coalescing is going to replace ||
in there:
const myColor = color ?? 'red'
Why is this operator useful?
Well, there is a whole range of bugs that hide underneath the surface when using ||
to provide a fallback value.
In short, ||
handles values as falsy. ??
handles values as nullish (hence the name).
Which means that with ||
the second operand is evaluated if the first operand is undefined
, null
, false
, 0
, NaN
or ''
.
??
on the other hand limits this list to only undefined
and null
.
THE VALLEY OF CODE
THE WEB DEVELOPER's MANUAL
You might be interested in those things I do:
- Learn to code in THE VALLEY OF CODE, your your web development manual
- Find a ton of Web Development projects to learn modern tech stacks in practice in THE VALLEY OF CODE PRO
- I wrote 16 books for beginner software developers, DOWNLOAD THEM NOW
- Every year I organize a hands-on cohort course coding BOOTCAMP to teach you how to build a complex, modern Web Application in practice (next edition February-March-April-May 2024)
- Learn how to start a solopreneur business on the Internet with SOLO LAB (next edition in 2024)
- Find me on X