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Oops, I did it again: A guide to debugging common JavaScript errors

Ali Spittel on March 25, 2019

Writing JavaScript code can sometimes make us feel like running, hiding, or just being scared. But, with some debugging tips we can get in the zone...

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Emma Bostian ✨ • Mar 25 '19

I literally don't have words

zeddotes • Mar 25 '19

Cannot read property 'words' of undefined.

kevin • Jun 11 '19

lol

Jochem Stoel • Mar 26 '19

function oneMoreTime(stillBelieve=true, loneliness=0) {
    if (!stillBelieve && loneliness < 0) return
    loneliness++
    return oneMoreTime(stillBelieve, loneliness)
}

This is poetry.

David Wickes • Mar 26 '19

First, if you're in an infinite loop, quit the tab if you're in Chrome or Edge, and quit the browser window in FireFox.

FireFox is a lot friendlier than this - you don't need to close the whole browser and you get a nice, friendly message:

too much recursion indeed!

Andy Zhao (he/him) • Mar 25 '19

Big fan of the Bracket Pair Colorizer extension! Before, I didn't know that something wasn't right, and it definitely gives you a sign!

dAVE Inden • Mar 26 '19

I didn’t know about this extension. I’m totally going to try it out. It seems like it would save me a bunch of time.

Laurie • Mar 25 '19

So now the question is which of the referenced songs am I listening to first...

I've always been partial to Everytime :)

Gabriele Cimato • Mar 25 '19

Ahah brilliant!

Anna Rankin • Mar 25 '19

Nice one Ali! We recently started using Prettier on one of our projects and I love it - it catches silly mistakes and quells syntax debates 🤘 thanks as always!

Noorullah Ahmadzai • Mar 25 '19

const Ali = {
Name: 'Ali',
LovesBritney: true,
ShoutOut: function(){
console.log('Ali is awesome');
}

Ali.ShoutOut();

😅

Noorullah Ahmadzai • Mar 25 '19

Loved the way you explained the full stack issue, the rest I had a basic info about!
Still learnt something new 😃

Rafael Oliveira • Mar 25 '19

It's wonderful!!!
Sometimes these errors makes anyone Crazy, but Everytime I got these errors, I'll remember this text.

Davina Leong • Mar 25 '19 • Edited

#britneyspears

Sorry, just can't help myself when I saw the title...

Neil Syiemlieh • Mar 26 '19

Read this last night and "Lucky" was stuck in my head all day today

Celso de Sá • Mar 26 '19

Using StandardJS?

Colin Domansky • Mar 25 '19

Wow!

dAVE Inden • Mar 26 '19

This post is great! Ali has tons of info here with links to other resources too. This is a great resource for learning about why some of these really common errors happen. Nice work!

Jeremy Moore • Apr 19 '19

I need to write a post on a great follow up to this: debugging closures. I'm reminded of a big blocker I encountered when trying to debug an inner function one time.

Juliano Rodrigues • Mar 25 '19

Really good article! Thanks