Sparkline Generator

Create compact inline sparkline charts as SVG from numeric data.

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Input
Output
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About sparkline generator

Sparkline Generator loads once and then runs on its own. Close the tab and there is nothing left behind, on the machine or anywhere else.

Everything after the first page load is local. Pull the network cable mid-edit and the tool carries on as though nothing happened.

You will find it under Charts, alongside 7 other tools for the same sort of job.

Supports fill color, dot markers, and min/max highlighting.

How to use it

01
Start it
Every control is on the tool itself. Keyboard shortcuts, where there are any, are listed beside it.
02
Watch it run
It updates in the page as you go. Nothing is sent anywhere, so it keeps working with the network off.
03
Close when done
Nothing is stored between visits. Reloading gives you a clean start rather than picking up where you left off.

Examples

Stock Sparkline
Generate a mini sparkline for stock price trend
Input
data: [10,15,13,17,20,18,22,25]
width: 150
height: 30
color: #4e79a7
strokeWidth: 1.5
showDots: false
showMinMax: true
Output
<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 150 30" width="150" height="30"><path d="M 2 28 L 22.857142857142858 19.333333333333336 L 43.714285714285715 22.8 L 64.57142857142857 15.866666666666667 L 85.42857142857143 10.666666666666668 L 106.28571428571429 14.133333333333333 L 127.14285714285714 7.199999999999999 L 148 2" fill="none" stroke="#4e79a7" stroke-width="1.5" stroke-linecap="round" stroke-linejoin="round"/><circle cx="2" cy="28" r="2.5" fill="#e15759"/><circle cx="148" cy="2" r="2.5" fill="#59a14f"/></svg>

Questions

Does Sparkline Generator work offline?+

Yes. It is JavaScript running in this tab, so once the page has loaded it needs nothing further from the network. Put the machine in flight mode and it carries on. Nothing you do here is sent anywhere, because there is nowhere for it to go.

Does it remember anything between visits?+

No. Reload the page and it starts from nothing. There is no account, no saved state and no cookie holding your last session. That is a deliberate trade: it cannot lose your data because it never keeps any.

Is it accurate?+

Timing comes from performance.now(), the high resolution clock the browser provides, rather than from setInterval, which drifts by a few milliseconds every tick and compounds over minutes. What can still shift things is the browser throttling a tab in the background, so leave it visible if the timing matters.

Does it make a sound?+

Where a sound makes sense, it is generated with the Web Audio API rather than loaded as a file, so there is nothing to download and nothing to block. Browsers refuse to start audio until you have interacted with the page, which is why the first press is what switches it on.

Can I use Sparkline Generator on a phone?+

Yes. The controls are sized for touch and the layout collapses to one column on a narrow screen. Bear in mind that a phone locking its screen will suspend the page, and timing stops with it.