Guides
Step-by-step walkthroughs: from idea to deploy. Practice for total beginners.
Why my page jumps when a modal opens — and why you can't see it on a Mac
Does your page shift sideways when a modal opens? Here's the cause — a disappearing scrollbar — and the fix with scrollbar-gutter: stable and padding-right.
How to detect an element's size change — and why window.resize stays silent
How to detect an element's size change in JavaScript: step by step with ResizeObserver, why window resize doesn't fire, and how to fix the ResizeObserver loop error.
Why my numbers jump when they change — the timer jitters and the text next to it moves
Why a timer or counter jitters and shifts the text beside it: proportional digits, changing digit count, and fonts without tabular-nums. How to fix it.
How to make a carousel (slider) with CSS — no library, native swipe
How to build a pure-CSS carousel with scroll-snap: native swipe on phones, arrows and dots in 20 lines of JS, no slider library and no broken Back gesture.
Why your download link opens the file instead of downloading it — 3 causes
The download attribute not working and your PDF opens in a tab? Three causes — a different domain, fetching without saving, and in-app browsers — and how to fix each.
How to make font size responsive — and why font-size in vw breaks zoom
How to make responsive font size in CSS with clamp(): a two-point formula, ready-made values, and why font-size in pure vw refuses to grow when users zoom in.
Why fetch returns stale data — 3 caching causes and how to fix them
fetch returns stale data even though the database has new data? We cover 3 caching causes: Next.js built the page at build time, the browser cache, and a CDN.
How to calculate the number of days between two dates in JavaScript — and why you get one day too few
How to calculate days between two dates in JavaScript without an off-by-one: time of day, time zones, input type=date and Temporal. A ready function plus tests.
Why changing one item changes all of them — three causes and fixes
Changed one item and they all changed? Three reasons every array item changes at once: fill, an object reused in a loop, a shared default — and fixes.
How to capitalize the first letter — without turning iPhone into Iphone
How to capitalize the first letter of a string in JavaScript and CSS: step by step, with empty strings, leading quotes, Turkish i and names like McDonald.
Why you get NaN in JavaScript — 3 causes and how to find where it came from
Why JavaScript gives you NaN instead of a number: an empty field, text instead of a number, zero divided by zero. How to find the source of NaN and fix it fast.
How to convert a string to a number in JavaScript — without tripping on a comma
How to turn a string into a number in JavaScript: Number, parseInt or parseFloat. Step by step — with empty fields, spaces in "1 200" and a decimal comma.
Why my loop never stops — and the tab freezes solid
An infinite loop: the tab froze, the fan is screaming, the server gets thousands of requests. Three real causes — from React useEffect to while — how to check and fix.
Why my array is empty — and why there's no error
The array is empty, the screen shows nothing, the console is silent. Three real causes of an empty array — data not there yet, a filter that cut everything, a list nested deeper — and how to check each.
Why your AI agent edits the wrong file — three causes and how to check each
The agent says «done» and nothing changed in your app. Three real causes: wrong folder, a twin file with the same name, and editing generated code.
How to write an Agent Skill (SKILL.md) — in one evening, no code
Step by step: create the folder, write SKILL.md, get the agent to pick it up by itself. Plus the fix for the one mistake that keeps skills from firing.
Why my tests pass locally but fail in CI — 3 real causes
Green locally, red in CI. The three real causes of tests failing in CI — and why, in that argument, CI is usually right and your machine is the liar.
Refactor or rewrite — and why the agent always votes for the rewrite
Agents almost always suggest rewriting — because rewriting is cheaper for them than understanding. Five criteria for when to refactor and when to start over.
How to review AI-generated code — and why you start with the diff
Models rarely write syntactically wrong code — they write plausibly wrong code. Six steps for reviewing AI-generated code that catch it in ten minutes.
Why the iPhone zooms in when you tap an input field
An input field zooms the page on iPhone because its font size is under 16px. How to check it, how to fix it, and why the maximum-scale advice only hurts.
How to truncate text with an ellipsis in CSS — step by step
How to truncate text with CSS: one property isn't enough, you need three. Single-line, multi-line clamping, and the flexbox trap that breaks both.
Why my page scrolls sideways on mobile — and how to find the culprit in a minute
Horizontal scrolling on mobile: three real causes and a snippet that names the guilty element instantly. Plus why overflow-x hidden is a bad fix.
How to center a div — 4 ways and when to use each
How to center a block horizontally and vertically: margin auto, flex, grid and the new align-content in a plain block. With code and a rule for picking one.
Why 100vh is taller than the screen on mobile — 3 causes and how to fix them
Your 100vh block spills past the phone screen and the button hides under the address bar? Three causes explained: browser bars, the keyboard, the gesture bar.
How to add a share button to your site — the phone's own share sheet, no social widgets
How to build a share button with the Web Share API: the phone's native share sheet, a fallback for desktop, and three mistakes that quietly break it.
Why your focus outline disappeared — 4 causes and how to bring it back
No focus outline when you press Tab? Four causes: outline: none in your CSS, a clipping parent, a sticky header and color — how to check and fix each.
How to add a “Copy” button — and why it stays silent on http
How to add a copy button to your site: navigator.clipboard in five steps, a “Copied” confirmation for screen readers, and three reasons copying fails.
Why position: sticky isn't working — 3 causes and how to find yours in a minute
Your position: sticky header scrolls away with the page? Three common causes — a missing top, overflow on a parent, no room to move — and how to check each.
How to make a custom 404 page — without getting a “soft 404” from Google
How to make a custom 404 page on Netlify, GitHub Pages, nginx, Next.js and in a React SPA — and check that the server answers 404, not 200.
Why does my page show 404 after refresh — when links inside the site work fine
A React or Vite site loads, clicking around works, but F5 on an inner page gives 404. Three causes and ready-made settings for Netlify, Vercel and nginx.
How to keep filters in the URL — so a link opens the same view and Back works
How to store filters, sort order and the active tab in the page address: six steps with URLSearchParams, pushState vs. replaceState, and ready-to-use code.
Why my form clears everything I typed — 3 causes and the fix
The form empties itself after an error and people retype it all. Three causes: a blank server re-render, a remounted component, and a Back that never restored.
How to build a multi-step form — so people actually finish it
A step-by-step walkthrough: how to split a long form into screens, where to keep the answers, how not to lose them on Back, and why you need a review screen.
Why my tooltip doesn't show on mobile — three causes and how to fix each
On desktop the tooltip appears on hover; on a phone it's missing or stuck. The three real causes — hover, the title attribute, clipping — and the fixes.
How to rewrite UI text with AI — step by step, with a ready-made prompt
By default a model writes 'Oops! Something went wrong'. Six steps and a ready prompt to get buttons and error messages that actually help people.
Why users don't see my error message — 3 causes and how to check each
"I clicked and nothing happened" — yet the error is displayed. Three reasons your error message never reaches the user, and a one-minute check for each of them.
How to replace "Are you sure?" with Undo — 5 steps and a working setup
How to add an undo action instead of a confirmation dialog: five steps with code — a delete flag, instant removal, the undo window, and what to do with timers.
Why the model refuses my request — and how to rephrase without cheating
Why the model refuses your request: a trigger word fired, context was missing, or it wasn't the model at all. Three causes, and what to do about each.
How to add content moderation to your app — five steps and zero cost
How to add content moderation to your app: a free endpoint, 13 categories, three outcomes instead of a ban, and checking the model's output too.
Why an API returns 401 — and how it differs from 403: 3 causes
A 401 error means 'I don't know who you are,' not 'you're not allowed.' Here's why an API returns 401, where to find the cause, and how to fix the 3 most common.
How to set up a cron job — so your script runs itself, on schedule
Step by step: how to set up a cron job, read its five-field syntax, and dodge the classic traps. Your script will run itself, without you.
Why images aren't loading on my site — 3 causes, starting with letter case
Images not loading on your site: a broken icon instead of a photo. We break down 3 causes — path and case, files missing from deploy, hotlinks — and fix each.
How to read an error message — the three-line method instead of panic
How to read an error message: find the type, the text and your own line in the stack trace. A three-line method that untangles the red wall in minutes.
Why your cron job isn't running — and how to make cron confess
Cron is silent on success and on failure alike. The three real reasons a cron job doesn't run: a bare environment, relative paths, a sleeping machine.
How to write a Git commit message — for future you and for AI
A commit message isn't a formality — it's a letter to future you and context for AI agents. The two-part format, a template, and good-vs-bad examples.
Why your bot stops when you close your laptop — and how to make it immortal
You close the laptop and the Telegram bot goes silent. Not a bug: a bot is a process on your machine, not a cloud. Three causes and three real fixes.
How to add a contact form to your site — so messages actually arrive
A step-by-step contact form for your site: the markup, sending without a page reload, where messages land — and a one-line spam trap.
Terminal commands every beginner needs — 8 to stop fearing the black window
Terminal commands for beginners: 8 of them, enough to calmly follow AI instructions — enter a folder, start a project, stop the server, repeat a command.
How to run a GitHub project locally — 5 steps from clone to localhost
How to run a GitHub project on your machine: git clone, installing dependencies, the .env file, and the first launch. Five steps — and someone else's code runs locally.
Why my webhook isn't firing — the three causes that catch everyone
Why your webhook isn't firing: it almost always fired. Three causes by frequency — localhost unreachable from outside, no 200 reply, a signature mismatch — and the fix.
What is a feature flag — and why code in production doesn't mean 'on'
What a feature flag is in plain words: a switch in production that separates 'code shipped' from 'feature visible.' Gradual rollout and a kill switch — with no new release.
How to add search to your app — from a simple filter to search by meaning
How to add search to your app: 4 levels from an in-memory filter to search by meaning. Start with one line of SQL — most projects never outgrow it.
Why is my AI bill so high — where your tokens actually leak
Your API bill jumped even though requests look the same. Here are the 3 main causes of a high AI bill — long context, an expensive model, loops — and how to fix each.
How to add rate limiting — a fuse against a 10,000-request bill
One buggy loop in AI-written code and an API gets hammered a thousand times a minute. Step by step: how to add rate limiting, from an in-memory counter to a ready library.
Git vs GitHub — why they're not the same thing at all
Git is a program on your laptop, GitHub is a website. Here's the difference between Git and GitHub in plain terms: what each one does and why you need both.
Why my JSON parse fails (Unexpected token) — 3 causes, none of them in the JSON
SyntaxError: Unexpected token — it's almost always just not JSON. Why JSON parsing fails: 3 real causes (the model wrapped it in ```json, the server sent HTML) and the fixes.
What is CI/CD — and why a green checkmark promises nothing
CI/CD is a robot that runs your checks on every commit. What CI/CD is in plain words, why it matters when you code alone, and why that green checkmark lies.
How to add image upload to your app — 5 steps and one trap
The classic beginner mistake is putting the image in the database. How to add image upload: 5 steps from input to URL, with checks, previews and size limits.
Port already in use — why it happens and how to fix it fast
The «port already in use» error almost always means an old process didn't close and is still holding the door. How to find what took the port and free it — step by step.
How to connect a frontend to a backend — step by step, with plain fetch
The frontend draws, the backend serves data, and a fetch request links them. Step by step: connect a frontend to a backend, show the data, and dodge the CORS error.
Why npm install fails — 4 causes and how to fix each
npm install fails mostly for 4 reasons: the Node version, a broken cache, a dependency conflict, or the network. Here's each one — how to check and how to fix, no full reinstall.
How to write tests with AI — lock your code against dumb breakage in 15 minutes
Tests catch bugs before your users do. Here's how to write tests with AI step by step — from picking a function to a green checkmark, even if you're a beginner.
Why Git shows a merge conflict — and how to clear it
CONFLICT in your terminal isn't a breakage — it's a question from Git. Here's why a merge conflict happens, and how to resolve it step by step without breaking your code.
What is an MVP — and why it isn't a 'stripped-down app'
An MVP isn't half a product — it's the cheapest way to test whether anyone wants it. Here's what an MVP really is, and how to build one over a weekend.
MVP or prototype — what's the difference and what to build first
People mix up MVP and prototype constantly, but they answer different questions. We compare MVP vs prototype by goal, audience, and lifespan — and say where to start.
How to undo a Git commit — 3 commands for 3 situations
Messed up a commit? Git almost never deletes anything for good. Here's how to undo a Git commit step by step — for both local and already-pushed commits.
Why my app works locally but breaks in production — 3 causes and the fix
'Works on my machine' — but production shows a blank screen or a 500. Same code, different environment. Here are the 3 main causes and how to check and fix each.
How to stream AI responses — so text types out letter by letter instead of hanging
Users wait 5 seconds at a blank screen for an AI reply and think it froze. Streaming paints text as it's generated. Here's how to do it, step by step with code.
Why git push is rejected — 3 causes and how to fix each
"! [rejected] fetch first" isn't a break — it's git protecting someone's work. The 3 real causes of a rejected git push and how to fix each.
How to add dark mode to your site — in 3 steps, no libraries
You don't redraw a site for dark mode: CSS variables and one media query do 80% of the work. A step-by-step guide to add dark mode from scratch.
Why your AI responses are slow — 3 causes and how to speed them up
AI taking forever to answer? Usually it's not the internet — it's the model, streaming, or a bloated context. Here are 3 causes of slow AI responses and a fix for each.
How to run an AI model locally on your laptop — in three commands
You can run a neural net on your own computer with no internet, no key, no bill — and your data never leaves. Here's how to run AI locally with Ollama.
Why fetch returns undefined even though the data is there — 3 causes
'The data arrives, I see it in the Network tab, but the variable is undefined.' Here are the 3 causes of fetch returning undefined — how to check each and fix it.
How to write a README — step by step, so a human and an AI both get it
Your README is read by both a new developer and an AI agent in your repository. Step by step: what to put in the file, in what order — and a skeleton to copy.
Why my page is blank (white screen) — 3 causes and the first thing to open
You open the site — a white screen, nothing there. Why the page is blank: 3 common causes (console error, wrong path, empty root) and how to fix each.
Web app or native app — which to build first, and why tech isn't the decider
Native app or web app — which to pick for your first project? We compare on cost, speed and reach and say plainly what a beginner should build.
How to make a landing page — from a blank page to a live link in one evening
A landing page has one job — one action. A step-by-step guide: how to make a landing page with AI, what belongs on it, and how to publish it for free.
Why AI cuts off its answer mid-sentence — 3 causes and the fix
AI stops mid-sentence? It's almost never a bug — it's a limit. Here are the 3 real causes of a cut-off, from max_tokens to a full context window, each with its fix.
How to cache AI responses — so you don't pay twice for one question
The same request makes the AI answer again and charge you every time. A cache breaks that loop: same question, instant answer, free. Here it is step by step.
How to make a Chrome extension — in an evening, even if you don't code
A Chrome extension is a folder with a manifest.json and a little code. Step by step: how to make a Chrome extension and load it into your browser in one evening.
Git commands every beginner needs — 7 that cover 90% of the work
You don't need all of Git. Here are 7 Git commands every beginner needs — from init to undo — that you'll actually use in your first month, with the catches.
How to give AI context about your code — so it stops guessing
AI writes off-target because it can't see your project. Here's a step-by-step way to give AI context about your code with a single file — so answers get accurate.
Why your environment variables aren't working — 3 common causes
Works locally, deploy it, and the variable is undefined? 90% of the time it's one of three causes. We cover each: how to check, how to fix.
How to add AI to your website — in one evening
Adding a chat or an 'ask AI' button to your site isn't months of work — it's one evening. You need a small server piece and a dozen lines. Step by step.
Why your CSS isn't working — 3 causes to start with (a hard refresh fixes half)
Why your CSS isn't working: you change a style but the page looks the same. The 3 common causes — cache, specificity, linking — and how to fix each.
How to send email from your app — step by step, without your own mail server
How to send email from your app: verification codes, receipts, password resets. Step by step through a ready service — no self-hosted SMTP, no evening of pain.
How to Speed Up Your Website — 5 Steps You Can Do in an Evening
Step by step: how to speed up your website with no developer — measure speed, compress images, add lazy loading and a CDN. Real steps, one evening.
How to cut your AI costs — 6 steps without losing quality
The same result can cost 10x less. You pay for tokens, not requests — and most beginners burn them for nothing. Here's how to stop.
Best free hosting for your first app — 7 working options and their catches
You can put your first site online for $0 in five minutes. But 'free' costs something different on each host — here's where it works, and the catch.
What is a pull request — and why it's not about 'pulling'
A pull request is a proposed change, reviewed before it merges. Here's what a pull request is, why you want one even solo, and how to use it.
How to choose an AI model for the job — not the most expensive one
How to choose an AI model for the job: step by step — reasoning, context, cost, and testing on your own examples. Default to cheap, raise the bar only when needed.
Why your site isn't showing in Google — 3 causes and how to fix each
A new site doesn't appear in Google right away, and is sometimes accidentally blocked from indexing by a single toggle. Here are the 3 real causes and fixes.
How to make an AI chatbot — step by step, from zero to working in an evening
An AI chatbot isn't training a neural net — it's three blocks: a model via API, a system prompt, and a simple interface. Here's what to do, in order.
How to add analytics to your site — in 10 minutes, no developer needed
Step by step: how to add analytics to your site, drop in the counter, check the first visit, and see how many people actually show up — in ten minutes.
Why your deploy fails when it works locally — 3 causes to check first
'Works on my machine, but the server says Build failed.' Here's why your deploy fails: the 3 most common causes, how to check each, and how to fix it.
Why AI-written code has bugs — 3 causes, and why it doesn't mean 'AI is dumb'
The AI gave you clean code and it crashes. Here's why AI-written code has bugs: 3 real causes, and what to do to get far fewer of them.
How to take your first payment — step by step, without becoming a bank or touching cards
To charge money in your app you don't store card numbers. A step-by-step walkthrough: add payments through a ready service in an evening, leak nothing.
What a 500 error means and how to fix it: 3 causes to start with
A 500 error means "the server crashed, not you." Here's what a 500 error means, where to find the cause, and how to fix the 3 most common ones.
How to use Git as a beginner — step by step, and why it's a time machine for code
Git isn't cloud storage for code — it's a time machine with save points. A step-by-step on how to use Git as a beginner: init, commit, push — five commands.
How to make a site mobile-friendly — step by step, starting with the one line everyone forgets
Site broken on phones? 9 times out of 10 it's one forgotten line. A step-by-step on how to make a site mobile-friendly — from viewport to checking it.
How to fix a CORS error — 3 causes and the fix for each
A CORS error can't be fixed on the frontend — headers in fetch won't help. Here's the symptom, 3 real causes, and the exact server-side fix for each.
How to debug with AI — 5 steps so it actually helps instead of guessing
'It doesn't work, fix it' is the worst way to ask AI to debug. Five steps: give the exact error, the context, and test one change at a time.
How to buy and connect a domain — step by step, and why it doesn't open right away
Buying a domain is easy; connecting it feels scary. Really it's two DNS records and some patience. A step-by-step guide: from picking a name to a working https address.
How to store API keys safely — and why a frontend .env isn't a secret
The classic beginner mistake: hiding a key in a frontend .env. At build time it lands in the bundle and anyone can see it. Here's how to store API keys properly.
Website launch checklist — 8 checks that actually matter
Before launch, don't 'polish the design' — check the site opens on a stranger's phone. 8 items that catch 90% of embarrassing launch-day failures.
How to add login to your app — step by step, without inventing passwords
You don't build auth from scratch: a ready service does it for you in 20 minutes. A step-by-step walkthrough — from picking a provider to a protected page and a session check.
Pre-launch security checklist — 7 checks you can do in an evening
Before you publish an app, 7 checks are enough to not hand your data and money to the first passing bot. A concrete list, no lecturing.
How to set up a database for your app — step by step, no server of your own
You don't need to run a server: a free database goes live in 10 minutes. A step-by-step walkthrough on Supabase — from empty project to your first row.
How to deploy your app — step by step, from a folder on your laptop to a link on the internet
Built an app with AI but it only lives on your machine? A step-by-step guide to putting it online for free and getting a link to share.
How to deploy your first app with no code — it's just giving it an address on the internet
"Deploy" sounds scary. It really just means "give your project a link other people can open" — and an agent does it for you in a couple of minutes.
Your first vibe-coding project: the trick is picking one small enough
From idea to deploy without writing a line by hand. The hardest part isn't the code — it's resisting the urge to add more.
From Idea to Spec: Plan Your Product Before You Build It With AI
A vague idea makes the AI guess. A clear spec makes it build. Here is how to turn "an app for X" into something you can actually ship.
Validate Before You Build: Check Your Idea Before Writing a Line of Code
Building is the fun part — which is exactly why people skip the boring question: does anyone actually want this? Here is how to find out in a weekend.
Debugging With AI: How to Fix What You Don't Fully Understand
When the AI-built thing breaks, panic is optional. A calm, repeatable method beats frantic re-prompting every time. Here is the loop that actually finds bugs.
From Prototype to Production: What Changes When Real Users Arrive
A demo only has to work for you, once. A product has to work for strangers, all the time. Here is what actually separates the two — and what to fix before launch.
Shipping Your First Paying Feature: From MVP to First Customer
Free users are not validation — they are a hobby. The hardest, most honest milestone in building is one stranger paying you once. Here is how to reach it.
Talking to Users: How to Get Feedback That Actually Improves Your Product
Most feedback is polite, vague, and useless. The good stuff has to be dug out with better questions. Here is how to interview users without fooling yourself.
Pricing Your First Product: How a Solo Builder Sets the First Price
Beginners price on fear and pick a number too low to matter. Price is a message, not a math problem. Here is how to set a first number you will not regret.
Your First Project With AI: From Idea to Deploy in One Evening
A step-by-step guide: take an idea, build it with AI, deploy to the internet. No prior experience needed.