Upgrade to Pro — share decks privately, control downloads, hide ads and more …

The Truth About Truthy & Falsy

Avatar for Swaroop SM Swaroop SM
April 10, 2015
Technology
1
56

The Truth About Truthy & Falsy

Deck demonstrating which values are truthy / falsy w.r.t a programming language.

Avatar for Swaroop SM

Swaroop SM

April 10, 2015
Tweet

More Decks by Swaroop SM

See All by Swaroop SM
Client-Side Data Modelling and more...
Avatar for Swaroop SM swaroopsm
0
59
ReactJS Awesomeness
Avatar for Swaroop SM swaroopsm
3
260
Testing JavaScript like a "BOSS"
Avatar for Swaroop SM swaroopsm
0
61

Other Decks in Technology

See All in Technology
2025年にHCP Vaultを学び直して見えた景色 / Lessons and New Perspectives from Relearning HCP Vault in 2025
Avatar for AEON aeonpeople
0
200
衝突して強くなる！ BLUE GIANTと アジャイルチームの共通点とは ― いきいきと活気に満ちたグルーヴあるチームを作るコツ ― / BLUE GIANT and Agile Teams
Avatar for naiban naitosatoshi
0
310
【Grafana Meetup Japan #6】Grafanaをリバプロ配下で動かすときにやること ~ Grafana Liveってなんだ ~
Avatar for よしたけ yoshitake945
0
230
AWSで推進するデータマネジメント
Avatar for かわなご kawanago
0
1k
生成AI時代のデータ基盤
Avatar for shibuiwilliam shibuiwilliam
6
3.6k
AWSで始める実践Dagster入門
Avatar for キタガワ kitagawaz
0
230
20250903_1つのAWSアカウントに複数システムがある環境におけるアクセス制御をABACで実現.pdf
Avatar for yhana yhana
2
340
絶対に失敗できないキャンペーンページの高速かつ安全な開発、WINTICKET × microCMS の開発事例
Avatar for microCMS microcms
0
390
AI駆動開発に向けた新しいエンジニアマインドセット
Avatar for kazue kazue
0
200
ChatGPTとPlantUML/Mermaidによるソフトウェア設計
Avatar for gowhich501 gowhich501
1
120
Kubernetes における cgroup v2 でのOut-Of-Memory 問題の解決
Avatar for Preferred Networks pfn
PRO
0
460
2025年になってもまだMySQLが好き
Avatar for yoku0825 yoku0825
8
4k

Featured

See All Featured
Let's Do A Bunch of Simple Stuff to Make Websites Faster
Avatar for Chris Coyier chriscoyier
507
140k
Building Better People: How to give real-time feedback that sticks.
Avatar for Will Jessup wjessup
368
19k
A better future with KSS
Avatar for Kyle Neath kneath
239
17k
Distributed Sagas: A Protocol for Coordinating Microservices
Avatar for Caitie McCaffrey caitiem20
333
22k
Connecting the Dots Between Site Speed, User Experience & Your Business [WebExpo 2025]
Avatar for Tammy Everts tammyeverts
8
520
Unsuck your backbone
Avatar for Amy Palamountain ammeep
671
58k
The Art of Programming - Codeland 2020
Avatar for Erika Heidi erikaheidi
55
13k
A designer walks into a library…
Avatar for Paul Jervis Heath pauljervisheath
207
24k
Designing for humans not robots
Avatar for Tammie Lister tammielis
253
25k
Embracing the Ebb and Flow
Avatar for Simon Collison colly
87
4.8k
No one is an island. Learnings from fostering a developers community.
Avatar for Antonio thoeni
21
3.4k
RailsConf & Balkan Ruby 2019: The Past, Present, and Future of Rails at GitHub
Avatar for Eileen M. Uchitelle eileencodes
139
34k

Transcript

  1. WTF (What’s Truthy Falsy) Swaroop SM Cybrilla Technologies

  2. - TRUTHY: If the value isn’t literally “true” but evaluates

    to true. - FALSY: If the value isn’t literally “false” but evaluates to false. What is it?

  3. undefined 0 false “” null NaN nil [] {} true

    True False None

  4. var a = 0; if(a) { alert(“I’m TRUTHY :)”); }

    else { alert(“I’m FALSY. Feel so proud. :D”); } The Confusion

  5. TRUTHY - true - 0 - “” - [] -

    {} Ruby FALSY - false - nil

  6. Ruby on Rails present? - !blank? - 0 - true

    blank? - nil - “” - [] - {} - false - whitespace

  7. Python TRUTHY - True - 1 FALSY - False -

    None - 0 - [] - “” - {}

  8. JavaScript TRUTHY - true - “0” - [] - {}

    FALSY - 0 - false - “” - undefined - null - NaN

  9. Thank You! @smswaroop http://www.github.com/swaroopsm/truthy-falsy