Galton box animation: Difference between revisions

=={{header|JavaScript}}==

Works with NodeJs

<lang JavaScript>const readline = require('readline');

const galtonBox2 = (layers, balls) => {

const speed = 100;

const ball = 'o';

const peg = '.';

const result = [];

const sleep = ms => new Promise(resolve => {

setTimeout(resolve,ms)

});

/**

* The board is represented as a 2D array.

* @type {Array<Array<string>>}

*/

const board = [...Array(layers)]

.map((e, i) => {

const sides = Array(layers - i).fill(' ');

const a = Array(i + 1).fill(peg).join(' ').split('');

return [...sides, ...a, ...sides];

});

/**

* @return {Array<string>}

*/

const emptyRow = () => Array(board[0].length).fill(' ');

/**

* @param {number} i

* @returns {number}

*/

const bounce = i => Math.round(Math.random()) ? i - 1 : i + 1;

/**

* Prints the current state of the board and the collector

*/

const show = () => {

readline.cursorTo(process.stdout, 0, 0);

readline.clearScreenDown(process.stdout);

board.forEach(e => console.log(e.join('')));

result.reverse();

result.forEach(e => console.log(e.join('')));

result.reverse();

};

/**

* Collect the result.

* @param idx

*/

const appendToResult = idx => {

const row = result.find(e => e[idx] === ' ');

if (row) {

row[idx] = ball;

} else {

const newRow = emptyRow();

newRow[idx] = ball;

result.push(newRow);

}

};

/**

* Move the balls through the board

* @returns {boolean} True if the there are balls in the board.

*/

const iter = () => {

let hasNext = false;

[...Array(bordSize)].forEach((e, i) => {

const rowIdx = (bordSize - 1) - i;

const idx = board[rowIdx].indexOf(ball);

if (idx > -1) {

board[rowIdx][idx] = ' ';

const nextRowIdx = rowIdx + 1;

if (nextRowIdx < bordSize) {

hasNext = true;

const nextRow = board[nextRowIdx];

nextRow[bounce(idx)] = ball;

} else {

appendToResult(idx);

}

}

});

return hasNext;

};

board.unshift(emptyRow());

result.unshift(emptyRow());

const bordSize = board.length;

const apex = board[1].indexOf(peg);

return (async () => {

while (balls) {

board[0][apex] = ball;

balls = balls - 1;

await sleep(speed);

show();

iter();

}

await sleep(speed);

show();

while (iter()) {

await sleep(speed);

show();

}

await sleep(speed);

show();

})().then(() => console.log('Done!'));

};

galtonBox2(12, 50);

</lang>

{{out}}

<pre>

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o

o

o

o

o o

o o

o o

o o o

o o o

o o o o

o o o o

o o o o o

o o o o o o

o o o o o o o

o o o o o o o o </pre>