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Strip Flow type annotations to produce runnable JavaScript, using Babel.
Input
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Output
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Status
Ready
Time
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This conversion runs on our server to use a Node-only library. Your input is processed for the request and never stored.
Flow to JavaScript is a free online converter on AltFTool that strips Flow type annotations to produce runnable JavaScript, using Babel — no signup and nothing to install.
The conversion runs on AltFTool's server: your input is sent to the AltFTool API, converted, and returned to your browser. It is not stored. Flow to JavaScript is powered by the @babel/preset-flow library, and the JavaScript result can be copied or downloaded as flow-to-javascript.js.
Flow source is JavaScript carrying Flow type annotations, which is why the input is handled as JavaScript — paste the annotated file exactly as it appears in your project.
| Input format | Flow (JavaScript syntax) |
|---|---|
| Output format | JavaScript |
| Output file | flow-to-javascript.js (text/plain) |
| Runs | On AltFTool's server — the input is sent to our API and not stored. |
| Library | @babel/preset-flow |
| Category | Flow converters on AltFTool |
Open Flow to JavaScript on AltFTool — the converter loads straight away, with no account.
Paste your Flow into the left-hand input pane, or press Sample to load a working example.
About 300ms after you stop typing, AltFTool posts your input to its conversion API and puts the JavaScript output in the right-hand pane.
If this converter exposes options, open Settings to change them — the output re-runs as you adjust.
Copy the JavaScript output with the Copy button, or download it as flow-to-javascript.js.
Yes — this one runs on the server, because @babel/preset-flow is a Node library rather than a browser one. Your Flow is sent to the AltFTool API, converted, and returned. It is not stored.
The @babel/preset-flow library, running on AltFTool's server. The JavaScript you see is that library's output rather than an approximation written here.
Yes. Server-side converters accept up to 200,000 characters of input per request; anything larger is rejected with a "too large" error instead of being truncated.
The result is JavaScript. Copy it from the output pane in one click, or download it as flow-to-javascript.js — AltFTool names the file after the converter and serves it as text/plain.
Yes. Flow to JavaScript is free to use on AltFTool, with no account and no sign-up.
Drop the live Flow to JavaScript workspace into your own docs page, tutorial or blog post with one snippet. Free, responsive, light and dark — just keep the “Widget by AltFTool” credit link visible.
<iframe src="https://www.altftool.com/embed/widget/transform/flow-to-javascript"
title="Flow to JavaScript Converter — free AltFTool widget"
width="100%" height="820" style="border:0;border-radius:12px;overflow:hidden"
loading="lazy" referrerpolicy="no-referrer-when-downgrade" allow="clipboard-write"></iframe>
<p style="font-size:12px;margin:4px 0 0">Widget by <a href="https://www.altftool.com/transform/flow-to-javascript?utm_source=embed&utm_medium=widget" rel="nofollow">AltFTool — free online tools</a></p>More of AltFTool's Flow and format tooling, and the guides around it.