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Where your work goes

Open tabs come back when you start JSpark again. The Library keeps what you choose.

On this page

Open tabs are kept
Close a tab
Keep a Snippet in the LibraryJSpark+
Take your code out
Back up everything

There is no file to save or open. JSpark keeps your code for you, in two places: your open tabs, and the Library.

Open tabs are kept

JSpark saves your open tabs as you type. The next time you start it, every tab comes back as you left it: the code, the tab’s name, where the cursor was, and its Language and Load Mode.

// A small demo, so there is something to run. Clear it and write your own.

// Three tabs, one HTML file — and this is the tab that runs.

import { useEffect, useState } from "react"

1⌄// A small demo, so there is something to run. Clear it and write your own.

2⌄// A `//?` after a line shows what it came to; hover the value for every pass.

3⌄const scores = [12, 7, 30, 4]

4⌄

5⌄let total = 0

6⌄for (const score of scores) {

7⌄ total += score //? → 53

8⌄}

9⌄

10⌄console.log("total", total)

11⌄console.log("highest", Math.max(...scores))

12⌄

total 53

highest 30

Done in 4ms·Runs as you typeJSpark

Each tab is one Snippet. All three come back the next time you start JSpark.

The output is not kept. Run a Snippet again to see it.

Close a tab

Closing a tab closes its Snippet for good. If it has changes that are not in the Library, JSpark asks first. Click Back to keep it open, or Close to close it.

A tab that still shows its Starter’s demo, or a Saved Snippet just as you opened it, closes without asking. To stop the question, turn off Settings → General → Ask before closing unsaved work.

Keep a Snippet in the Library JSpark+

To keep a Snippet after its tab is closed, add it to the Library:

Click Add to Library, the bookmark on the rail, or choose File → Add to Library…
Check the Title. It starts as the tab’s name.
Add Notes and Tags if you like. They help you find it later.
Click Save. The bookmark fills for a moment.

import { addDays, format } from "date-fns"

1⌄import { addDays, format } from "date-fns"

2⌄

3⌄const due = addDays(new Date(2026, 8, 28), 30)

4⌄

5⌄console.log(format(due, "EEEE, d MMMM"))

6⌄console.log(format(due, "yyyy-MM-dd"))

Wednesday, 28 October

2026-10-28

Done in 9ms·Runs as you type

Add to Library asks for a Title, Notes and Tags; the Library then finds the Snippet by any of them.

A Saved Snippet is a copy. Changing the tab afterwards does not change it, and saving again makes a second Saved Snippet. Open the Library with ⌘⇧L or Ctrl+Shift+L. See The Library.

Saving to the Library needs JSpark+. In JSpark, everything already saved stays readable: you can search, open, copy and export it.

Take your code out

To use your code somewhere else, copy it:

In a tab, press ⌘A or Ctrl+A to select all the code, then ⌘C or Ctrl+C to copy it.
In the Library, click Copy code under a Saved Snippet.

Back up everything

Export Library saves every Saved Snippet to one file. It works in JSpark and JSpark+.

Choose File → Export Library…, or click … at the bottom of the Library’s list and choose Export Library…
Choose where to save the file. JSpark names it after the day, such as JSpark Library 2026-09-30.json.

Export Library…

Import Library…

New snippet

The … button at the foot of the Library's list exports or imports a Library.

The file holds each Saved Snippet’s title, notes, Tags and code, as JSON you can read in any text editor. Your open tabs are not in it: add a Snippet to the Library first, or copy its code.

In JSpark+, Import Library… reads such a file back, on this computer or a new one. It only adds: a Saved Snippet already in the Library is kept as it is. See Export and import.

The pictures show JSpark on a Mac. On Windows, the window looks a little different and uses Ctrl for ⌘, but everything works the same way.