How to Run JavaScript, TypeScript and React on iPhone

Short answer: you can write and run JavaScript on an iPhone or iPad with JavaScript Editor: JS IDE. Tap Run and your code executes on the device, with a console for logs, warnings and errors. It also runs TypeScript and React (JSX) with a live preview.

What it can do

Who it suits

Web developers testing an idea away from a laptop, students learning JavaScript, and anyone practising for a coding interview.

FAQ

Can I use npm packages on an iPhone? Yes, imports resolve when you run.

Do I need a build step for TypeScript? No, TypeScript runs directly.

Can I share what I build? Yes, publish it to a link.

Download JavaScript Editor: JS IDE on the App Store · Get it on Google Play for Android

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Meanwhile, the toolkit

~/cosmovex/home.md · rendered with Markdown Editor & MD Viewer

A Markdown editor good enough to write its own homepage.

This page is a Markdown document. You're reading the rendered preview — press or hit if you don't believe it. That round trip — plain text in, a clean document out — is what Markdown Editor & MD Viewer does on your Android phone. Free, offline, no account.

markdown Live Server — 2 editors, 1 file
# Two cursors, one document
My phone is hosting this file over Wi-Fi,
and my desktop is ed
> nothing leaves the device — it's your Wi-Fi, your file
▶  Install free on Google Play★ 4.7 on Play · 10,000+ installs · free

## New in v1.5 — watch it work

✓Version History — every save snapshotted; browse and restore
✓Works offline — no account, no cloud — files stay on your device

## Just shipped

Both offline-first, both free to try.

NEWAspenote: Offline Voice to TextIt writes it down. On your phone.Runs Offline · Nothing Uploaded · Summary & Actions
NEWHostPilot: PHP Server & SQLTurn your phone into a web server.PHP 8.4 & SQLite · Stays Running · SQL Console

## The rest of the toolkit

One app per job. No 200 MB do-everything bloat.

AppJobRating
Markdown Editor & MD ViewerWrite and preview Markdown on mobile.4.7★ · 5K+installios
WebEva: Build Websites & CodeBuild websites from your phone.4.4★ · 5K+installios
PDF Viewer & Editor - AIEdit, convert & sign PDFs on mobile.4.9★ · 1K+installios
HTML Viewer & Editor - CodeView & edit HTML on mobile.4.6★ · 1K+installios
SQLite Editor & SQL LearnerManage SQLite databases on mobile.5.0★ · 1K+install
Python IDE - Offline CompilerWrite and run Python on your phone.4.1★ · 1K+install
Aspenote: Offline Voice to TextIt writes it down. On your phone.—install
HostPilot: PHP Server & SQLTurn your phone into a web server.—install
DevBuddy: Offline Dev ToolkitYour pocket developer toolkit.—installios
ShellPilot - Batch SSH ClientSSH terminal & SFTP on the go.— · 1K+installios
API Client -REST & HTTP TesterTest APIs anywhere, anytime.— · 500+installios
JSON Editor - Viewer & FormatView, edit & format JSON instantly.— · 500+installios
Java & Kotlin Compiler IDEWrite and run Java on your phone.4.4★ · 1K+install
XML Viewer & EditorView, edit & validate XML on mobile.— · 5K+installios
Open CSV — Viewer & EditorOpen and edit CSV files on mobile.— · 500+installios
JavaScript Editor — React IDERun JavaScript and React on your phone.— · 1K+install
Image to SVG Converter, ViewerConvert images to SVG and edit vectors on mobile.— · 1K+install
YAML / YML Viewer & EditorView, edit & validate YAML instantly.— · 500+install
Network Toolkit: WiFi IP ToolsNetwork utilities and diagnostic tools.— · 500+install
Code Editor - Text & NotepadEdit text files on mobile.— · 500+install
C / C++ Compiler IDECompile & run C and C++ on your phone.—install
Diagram Maker: Flow & ERDDraw flowcharts & ERDs on mobile.—install
QR Scanner & GeneratorScan codes with confidence—install
Zip Extractor — Unzip RAR 7ZOpen ZIP, RAR, and 7Z files—install
PromptCrate: AI Prompt ManagerYour personal AI prompt library—install

## Free web tools

Background RemoverSnapglowSQLite ViewerQueryDrill

## Questions, answered

Is there a free Markdown editor for Android?

Yes — Markdown Editor & MD Viewer is free on Google Play. It gives you a split-view editor with live preview, syntax highlighting, and HTML/PDF export, and it works fully offline with no account.

Can I edit Markdown from my phone on a desktop browser?

Markdown Editor & MD Viewer includes a Live Server: your phone hosts the document over Wi-Fi and you edit it from any desktop browser with two-way live sync. The file never leaves your device.

Can I make Mermaid diagrams on Android?

Yes — the built-in Mermaid Studio turns plain text into flowcharts, sequence and class diagrams, with pan/zoom and SVG export, right on your phone.

Can I turn Markdown into slides or a PDF on my phone?

Presentation Mode turns any Markdown document into a fullscreen slide deck, and export produces styled HTML or print-ready PDF — all generated on-device.

## From the journal

We're a small studio with one rule: each app does a single job well, works offline, and never asks who you are.

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