Spin the Wheel

How the wheel picks a winner

1. Your list becomes slices. Each line is one entry. An entry with one share gets one slice of equal width; Ada *3 gets a slice three times as wide.
2. The winner is drawn first. When you press Spin, the page asks the browser's cryptographic generator for a random whole number between 0 and the total number of shares minus one. That number falls inside exactly one entry's shares, and that entry is the winner.
3. A resting point is drawn. A second random value decides where inside the winning slice the pointer stops, so it does not always land dead centre.
4. The wheel turns to it. The wheel makes five to seven full turns and slows down until the pointer rests on that point. The animation follows the draw; it never changes it.

Because the draw happens before the animation, the result is the same whether you watch on a fast laptop, a slow phone or with animations switched off in your system settings. In that last case the wheel jumps straight to the result.

Example: a weighted wheel with four names

Take four entries: Ali, Beatriz and Chen with one share each, and Dara written as Dara *3. That makes six shares in total.

The page draws one number from 0 to 5. If it is 4, Dara wins, and the wheel turns until the pointer sits somewhere inside Dara's half of the wheel.

Chance per entry on an unweighted wheel

With equal shares every entry has a chance of 1 divided by the number of entries. Where a name sits on the list makes no difference, as the run of 80,000 spins below shows.

Using the wheel in a classroom

• Paste the class list once and save it under the class name. It is there the next time you open the page on the same computer.
• Press Present to fill the screen with the wheel and the winner, which is easier to read from the back of the room. Press Esc to leave.
• Tick Remove winner after each spin when every student should get exactly one turn.
• To split the class instead of picking one person, use the random team generator. To set a speaking order for everyone, use the random order generator.

Using the wheel for a giveaway or on a stream

• Paste the entrants, one per line. If someone earned extra entries, write them once with a weight (name *2) instead of pasting the name twice.
• Switch the sound on or off with the sound button. The setting is remembered.
• For a stream overlay, open the wheel with ?transparent=1 at the end of the address. Only the wheel and the winner are shown and the page background is transparent.
• The last 10 winners stay listed under the wheel until you clear them, so you can read them back after the draw.
• For a draw without the animation, paste the same list into the random winner generator. To give every entrant a ticket number instead, use the number generator with names.