256 color terminal demo

colors.ts

export enum Ground {
	Fore = 38,
	Back = 48,
}

const code = (
	param: string | number | string[] | number[],
	suffix: string = '',
): string => {
	if (Array.isArray(param)) {
		param = param.join(';');
	}

	return ['\x1b[', param, suffix].join('');
};
const textFormat = (param: string | number | string[] | number[]): string =>
	code(param, 'm');
const color256 = (value: number, ground: Ground): string =>
	textFormat([ground, 5, value]);

let colorTable = '';
const doubleBreaks = [15, 51, 87, 123, 159, 195, 231, 255];
[
	7,
	15,
	21,
	27,
	33,
	39,
	45,
	51,
	57,
	63,
	69,
	75,
	81,
	87,
	93,
	99,
	105,
	111,
	117,
	123,
	129,
	135,
	141,
	147,
	153,
	159,
	165,
	171,
	177,
	183,
	189,
	195,
	201,
	207,
	213,
	219,
	225,
	231,
	237,
	243,
	249,
	255,
].forEach((line, n, breaks) => {
	const start = (n > 0) ? breaks[n - 1] + 1 : 0;
	const end = line + 1;

	let i = 0;

	for (i = start; i < end; i++) {
		colorTable += color256(i, Ground.Fore);
		colorTable += String(i).padStart(4, ' ').padEnd(5, ' ');
		colorTable += textFormat('');
	}

	colorTable += ' '.repeat(5);

	for (i = start; i < end; i++) {
		colorTable += color256(i, Ground.Back);
		colorTable += String(i).padStart(4, ' ').padEnd(5, ' ');
		colorTable += textFormat('');
	}

	colorTable += '\n';

	if (doubleBreaks.includes(line)) {
		colorTable += '\n';
	}
});

console.log(colorTable);