index.js

import chalk from 'chalk';

export default function sparkly(numbers, options = {}) {
	if (!Array.isArray(numbers)) {
		throw new TypeError('Expected an array');
	}

	let ticks = ['▁', '▂', '▃', '▄', '▅', '▆', '▇', '█'];
	const color = [[5, 5, 4], [5, 5, 3], [5, 5, 0], [5, 4, 0], [5, 3, 0], [5, 2, 0], [5, 1, 0], [5, 0, 0]];
	const finiteNumbers = numbers.filter(number => Number.isFinite(number));
	const minimum = typeof options.minimum === 'number' ? options.minimum : Math.min(...finiteNumbers);
	const maximum = typeof options.maximum === 'number' ? options.maximum : Math.max(...finiteNumbers);

	// Use a high tick if data is constant and max is not equal to 0.
	if (minimum === maximum && maximum !== 0) {
		ticks = [ticks[4]];
	}

	return numbers.map(number => {
		if (!Number.isFinite(number)) {
			return ' ';
		}

		let tickIndex = Math.ceil((number / maximum) * ticks.length) - 1;

		if (maximum === 0 || tickIndex < 0) {
			tickIndex = 0;
		}

		if (options.style === 'fire') {
			return chalk.rgb(...color[tickIndex])(ticks[tickIndex]);
		}

		return ticks[tickIndex];
	}).join('');
}