Category
Commands, patterns and defaults, laid out for scanning rather than reading. Everything here has been used on a real project, and anything with a sharp edge says so next to it.
28 notes · #cheatsheet #reference #quickref #commands
28 notes
Cheatsheets
Code gets read far more often than it gets written. Good DX means the next person, often you in six months, can tell what a name means, what a function expects and why it failed, without digging.
17 minIntermediate
Cheatsheets
An AI assistant can only use what it can reach. MCP is one standard plug, so the same assistant can read your design file, open a ticket or call an API without someone writing a custom bridge for each.
16 minIntermediate
Cheatsheets
A protocol is the agreed way two programs talk, like the rules of a phone call. Some ask a question and wait for an answer, some keep the line open, and some drop a message in a box for whoever comes to collect it.
14 minIntermediate
Cheatsheets
Google reads your page before anyone else does. SEO is making sure it can find the page, understand what it is about, and see that it loads fast, so it shows the page to the people looking for it.
13 minBeginner
Cheatsheets
The terminal is a conversation with the computer: you type a short command, it answers in text. Most servers have no other interface, so these commands are how real apps get deployed, inspected and fixed.
15 minBeginner
Cheatsheets
nano is the text editor already installed on nearly every Linux server. The two lines at the bottom of the screen always show the keys, so you can open a config file, change a line and save without memorising anything first.
9 minBeginner
Cheatsheets
MongoDB stores each record as a self-contained document, like a filled-in form, so everything about one thing can sit together instead of being split across tables.
13 minIntermediate
Cheatsheets
Instead of every part of the app building the tools it needs, NestJS builds each tool once and hands it to whoever asks for it, the way a workshop keeps one shared toolbox.
16 minIntermediate
Cheatsheets
PostgreSQL keeps data in tables that point at each other, like linked spreadsheets, and answers questions about them in a language called SQL.
13 minIntermediate
Cheatsheets
Redis keeps data in memory instead of on disk, so it answers in well under a millisecond. Apps use it as a fast scratchpad for caches, counters, queues and sessions.
12 minIntermediate
Cheatsheets
TypeScript is JavaScript with labels. You write down what kind of value each thing holds, and the editor tells you about a mistake before you ever run the code.
18 minIntermediate
Cheatsheets
A job queue lets the app hand slow work, like sending an email, to a background worker, so the user gets a reply right away instead of waiting for it to finish.
7 minIntermediate
Cheatsheets
Kafka keeps every message in an ordered log that many readers can go through at their own pace. RabbitMQ hands each message to the queues that want it and removes it once it is handled.
7 minIntermediate
Cheatsheets
Observability means your service can tell you when it is slow, failing or backed up. Metrics say something is wrong, traces say where, and logs say why.
7 minIntermediate
Cheatsheets
Every request passes the same checkpoints in the same order before it reaches your code. Once you know the order, you know where each piece of code belongs.
10 minIntermediate
Cheatsheets
Socket.IO keeps a live line open between the browser and the server, so either side can send a message the moment something happens instead of waiting to be asked.
12 minIntermediate
Cheatsheets
A migration is a small, numbered script that changes the database, like adding a column. Every copy of the app runs the same scripts in the same order, so every database ends up the same shape.
7 minIntermediate
Cheatsheets
Lodash is a drawer of small, well tested kitchen tools for data. Instead of writing your own loop to group, sort or safely dig into a list, you reach for the tool that already does it.
14 minBeginner
Cheatsheets
An airport shows one moment on many clocks, one per city. moment-timezone does the same for your code, so a meeting at 9am in London shows the right time in Tokyo, even when the clocks change for summer.
14 minIntermediate
Cheatsheets
JavaScript has one kind of number for whole numbers and decimals alike. It is very good at most maths, but a few decimals like 0.1 cannot be stored exactly, so tiny errors can creep in.
9 minBeginner
Cheatsheets
An object is a box of labelled things: a name, an age, an address. You look things up by their label, and you can add, change or remove labels whenever you like.
11 minBeginner
Cheatsheets
A Set is a bag that never holds the same thing twice. Drop in a value that is already there and nothing happens, which makes it the quickest way to remove duplicates.
7 minBeginner
Cheatsheets
A string is a line of text. You can measure it, search it, cut pieces out and change its case, but every change gives you a new string and leaves the old one exactly as it was.
9 minBeginner
Cheatsheets
A Symbol is a name tag that is guaranteed to be one of a kind. Two symbols with the same label are still different, so a key made from one never clashes with anyone else's.
7 minBeginner
Cheatsheets
Zod checks data at the door. You describe what a value should look like once, and Zod either hands it back clean or tells you exactly which part is wrong.
16 minIntermediate
Cheatsheets
An array is a numbered list. Its methods are ready-made tools for that list: one changes every item, one keeps only the items you want, one adds them all up into a single answer.
13 minBeginner
Cheatsheets
A function is a recipe with blanks in it, like "add ___ cups of flour". The blanks are the parameters, and what you actually pour in when you cook is the arguments.
12 minBeginner
Cheatsheets
A Map is a set of labelled drawers. You put something away under a name and later ask for it by that name. Unlike a plain object, the name can be anything, even another object.
10 minBeginner
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