Cli-Clock is a clock for your terminal. Once you run the program, it will display the current time on your terminal windo and ti will update every thirty seconds. The clock is formed by two characters, which are choosen from a preselected set of characters or passed as arguments by the user. Once the program starts, the application will measure …

cli-clock.js

/**
 * CLI-CLOCK 
 * 
 * Cli-Clock is a clock for your terminal. Once you run the program, it will display the current time on your 
 * terminal windo and ti will update every thirty seconds. The clock is formed by two characters, which are choosen 
 * from a preselected set of characters or passed as arguments by the user. Once the program starts, the application will 
 * measure the size of the current terminal window and display the time in the center of the window.
 * 
 * Example usage:
 * 
 * $ node cli-clock.js 
 * $ node cli-clock.js " " X
 * $ node cli-clock.js O 🐶 
 * $ node cli-clock.js 😁 😡
 * 
 * 
 */

function getRandom(arr) {
  return Math.floor(Math.random() * arr.length);
}

function Clock() {
  if (process.stdout.rows) {
    this.rows = process.stdout.rows;
    this.columns = process.stdout.columns;
  } else {
    this.rows = 20;
    this.columns = 50;
  }

	this.availableNumbers = {
		'5x8': [
			['11111', '10001', '10001', '10001', '10001', '10001', '10001', '11111'], // 0 
			['00001', '00001', '00001', '00001', '00001', '00001', '00001', '00001'], // 1
			['01110', '10001', '00001', '00010', '00100', '01000', '10000', '11111'], // 2
			['11111', '00001', '00001', '01111', '00001', '00001', '00001', '11111'], // 3
			['00110', '01010', '01010', '10010', '11111', '00010', '00010', '00010'], // 4
			['11111', '10000', '10000', '11110', '00001', '00001', '00001', '11110'], // 5
			['11111', '10000', '10000', '11111', '10001', '10001', '10001', '11111'], // 6
			['11111', '00001', '00010', '00100', '00100', '01000', '01000', '10000'], // 7
			['11111', '10001', '10001', '11111', '10001', '10001', '10001', '11111'], // 8
			['11111', '10001', '10001', '11111', '00001', '00001', '00001', '00001'], // 9
			['00000', '00000', '00100', '00000', '00000', '00100', '00000', '00000']  // :
		]
	};

	this.availableSets = [['•','X'], ['\\', '/'], ['-', '_'], ['0', '1'], [' ', '█']];

	this.numbersToUse = this.availableNumbers['5x8'];

	this.currentSet = this.availableSets[getRandom(this.availableSets)];


	if (process.argv[2] && process.argv[3]) {
		this.currentSet = process.argv.slice(2, 4);
	} else {
		// randomly reverse the array, so we can have a random BG and FG
		if (Math.round(Math.random())) {
			this.currentSet = this.currentSet.reverse();
		}
	}
	
	this.buffer = [];

	for (let i = 0; i < this.rows; i++) {
		this.buffer[i] = [];
		for (let h = 0; h < this.columns; h++) {
			this.buffer[i][h] = 0;
		}
	}
}

// returns the size of the first character in a set
Clock.prototype.getLetterDimensions = function(character) {
	return {
		width: character[0].split('').length,
		height: character.length,
		padding: 1
	}
}

Clock.prototype.getTotalWidth = function(numberSet) {
	const letterDimensions = this.getLetterDimensions(numberSet[0]);
	return (letterDimensions.width + (letterDimensions.padding * 2)) * 5;
}

Clock.prototype.getTotalHeight = function(numberSet) {
	const letterDimensions = this.getLetterDimensions(numberSet[0]);
	return (letterDimensions.height + (letterDimensions.padding * 2));
}

/**
 * Fill the background with zeros aka the background character
 */
Clock.prototype.setBg = function() {
	// cycle through all the columns putting a zero on every column
	this.buffer.map((curr, i) => {
		this.buffer[i].fill(0);
	});
}

/**
 * Replace the appropriate background characters with the foreground ones
 */
Clock.prototype.setFg = function(numbers) {
  const characterDimensions = this.getLetterDimensions(this.numbersToUse[0]);
	const totalTextWidth = this.getTotalWidth(this.numbersToUse);
	const totalTextHeight = this.getTotalHeight(this.numbersToUse);

	const terminalHorCenter = Math.floor(this.columns / 2); 
	const terminalOffset = terminalHorCenter - Math.floor(totalTextWidth / 2);
	
	const terminalVerCenter = Math.floor(this.rows / 2);
	const terminalVerOffset = terminalVerCenter - (characterDimensions.height / 2); 

	const numToDisplay = this.getTime();

	for (var h = 0; h < numToDisplay.length; h++) { // cycle through the time numbers
		const leftIndex = (h * (characterDimensions.width + (characterDimensions.padding * 2))) + terminalOffset;

		for (var i = 0; i < characterDimensions.height; i++) { // cycle through the height of the numbers
			const thisRow = this.numbersToUse[numToDisplay[h]][i].split(''); // the row from the number to cycle through
			this.buffer[terminalVerOffset + i].splice(leftIndex, thisRow.length, ...thisRow); // replace the sections of the buffer with the section from the number
		}
	}
}

/**
 * Helper to Clear out the background
 */
Clock.prototype.clear = function() {
	console.log('\033c');
}

/**
 * Get the numbers that will be displayed. Will come from the time object 
 */
Clock.prototype.getTime = function() {
	const d = new Date();
	const timeArr = d.toTimeString().slice(0, 5).split('');

	// convert the strings numbers into numbers
	timeArr.map((curr, i) => {
		timeArr[i] = parseInt(curr, 10);
	});

	// replace the colon with the colon index from the font array
	timeArr[2] = 10;
	return timeArr;
}

/**
 * Update the buffer
 */
Clock.prototype.update = function() {
	this.setBg();
	this.setFg();
}

/**
 * draw out the buffer
 */
Clock.prototype.draw = function() {
	let toPaint = '';
	
	this.buffer.forEach((row) => {
		let currentRow = row.reduce((prev, curr) => {
			return prev + this.currentSet[curr];
		}, '');

		toPaint += '\n' + currentRow;
	});

	this.clear();
	process.stdout.write(toPaint);
}


// LAUNCH

const clock = new Clock();

clock.update();
clock.draw();

setInterval(() => {
	clock.update();
	clock.draw();
}, 30000);