jdsutherland
Modern Front-End Development for Rails: B7 pg 164 server JSON ids are numbers causing javascript Array#includes to always return false
After completing the section Using Data in Stimulus (ends pg 167), I noticed something wrong with Ajax updates. After running the rake task to sell out concerts, things looked fine on initial browser load:
but after Ajax it would change from “Sold Out” to “0 Tickets Remaining”:
The data attributes looked like this:
So concertSoldOutValue was suspiciously being set to false. The issue is that Array#includes is called with a string on an array of numbers (always false):
concertElement.dataset.concertSoldOutValue = soldOutConcertIds.includes(
concertElement.dataset.concertIdValue
)
typeof soldOutConcertIds[0]: number
The ids coming from the server JSON are numbers. One solution is to convert the ids to a string:
class SoldOutConcertsController < ApplicationController
def show
concerts = Concert.includes(:venue, gigs: :band).all
sold_out_concert_ids = concerts
.select(&:sold_out?)
.map(&:id)
.map(&:to_s)
render(json: {sold_out_concert_ids: sold_out_concert_ids})
end
end
Perhaps TypeScript could be leveraged to prevent this kind of bug?
First Post!
noelrappin
Author of Modern Front-End Development for Rails
This is a really great catch, I’ll fix it in the next update.
Popular Pragmatic Bookshelf topics
Hello Brian,
I have some problems with running the code in your book. I like the style of the book very much and I have learnt a lot as...
New
Title: Web Development with Clojure, Third Edition - migrations/create not working: p159
When I execute the command:
user=> (create-...
New
Title: Hands-On Rust (Chapter 11: prefab)
Just played a couple of amulet-less games. With a bit of debugging, I believe that your can_p...
New
Hi,
build fails on:
bracket-lib = “~0.8.1”
when running on Mac Mini M1 Rust version 1.5.0:
Compiling winit v0.22.2
error[E0308]: mi...
New
This isn’t directly about the book contents so maybe not the right forum…but in some of the code apps (e.g. turbo/06) it sends a TURBO_ST...
New
A Common-Sense Guide to Data Structures and Algorithms, Second Edition by Jay Wengrow @jaywengrow
Hi,
I have the paperback version of t...
New
Title: Build a Weather Station with Elixir and Nerves: Problem connecting to Postgres with Grafana on (page 64)
If you follow the defau...
New
The markup used to display the uploaded image results in a Phoenix.LiveView.HTMLTokenizer.ParseError error.
lib/pento_web/live/product_l...
New
Modern Front-End Development for Rails - application does not start after run bin/setup (page xviii)
After some hassle, I was able to finally run bin/setup, now I have started the rails server but I get this error message right when I vis...
New
When running the program in chapter 8, “Implementing Combat”, the printout Health before attack was never printed so I assumed something ...
New
Other popular topics
I’ve been hearing quite a lot of comments relating to the sound of a keyboard, with one of the most desirable of these called ‘thock’, he...
New
This looks like a stunning keycap set :orange_heart:
A LEGENDARY KEYBOARD LIVES ON
When you bought an Apple Macintosh computer in the e...
New
In case anyone else is wondering why Ruby 3 doesn’t show when you do asdf list-all ruby :man_facepalming: do this first:
asdf plugin-upd...
New
If you are experiencing Rails console using 100% CPU on your dev machine, then updating your development and test gems might fix the issu...
New
Learn different ways of writing concurrent code in Elixir and increase your application's performance, without sacrificing scalability or...
New
Build highly interactive applications without ever leaving Elixir, the way the experts do. Let LiveView take care of performance, scalabi...
New
The V Programming Language
Simple language for building maintainable programs
V is already mentioned couple of times in the forum, but I...
New
Hi folks,
I don’t know if I saw this here but, here’s a new programming language, called Roc
Reminds me a bit of Elm and thus Haskell. ...
New
Develop, deploy, and debug BEAM applications using BEAMOps: a new paradigm that focuses on scalability, fault tolerance, and owning each ...
New
Curious what kind of results others are getting, I think actually prefer the 7B model to the 32B model, not only is it faster but the qua...
New
Latest in Modern Front-End Development for Rails
Categories:
Sub Categories:
Popular Portals
- /elixir
- /rust
- /wasm
- /ruby
- /erlang
- /phoenix
- /keyboards
- /python
- /js
- /rails
- /security
- /go
- /swift
- /vim
- /clojure
- /emacs
- /java
- /haskell
- /svelte
- /onivim
- /typescript
- /kotlin
- /crystal
- /c-plus-plus
- /tailwind
- /react
- /gleam
- /ocaml
- /flutter
- /elm
- /vscode
- /ash
- /html
- /opensuse
- /zig
- /centos
- /deepseek
- /php
- /scala
- /react-native
- /lisp
- /textmate
- /sublime-text
- /nixos
- /debian
- /agda
- /django
- /deno
- /kubuntu
- /arch-linux
- /nodejs
- /ubuntu
- /revery
- /spring
- /manjaro
- /lua
- /diversity
- /julia
- /markdown
- /slackware










