vasanthv

const formatDate = (datestring) => {
	const seconds = Math.floor((new Date() - new Date(datestring)) / 1000);
	let interval = seconds / 31536000;
	if (interval > 1) return Math.floor(interval) + "Y";
	interval = seconds / 2592000;
	if (interval > 1) return Math.floor(interval) + "M";
	interval = seconds / 86400;
	if (interval > 1) return Math.floor(interval) + "d";
	interval = seconds / 3600;
	if (interval > 1) return Math.floor(interval) + "h";

vasanthv

const captilize = ([fL, ...rest]) => fL.toUpperCase()+rest.join("");

vasanthv

String.prototype.mySubstring = function(start, end) {
	let substr = '';
	for (i = (start || 0); i <= ((end || this.length) - 1); i++) {
		substr += this[i];
	}
	return substr;
}


console.log("hello world!".mySubstring(1, 5)); // => ello

vasanthv

function isPrime(num) {
	if (num > 2 && num % 2 === 0) return false;
	for (var i = 3; i < Math.sqrt(num); i += 2) {
		if (num % i === 0) return false;
	}
	return num > 1;
}

vasanthv

const arr = [ [ '8', '0', '5', '7', '9' ], [ '1', '2', '4' ] ]

const output = arr.reduce((a, b) => {
	let ret = [];
	a.forEach(i => b.forEach(j => ret.push(i + j)));
	return ret;
});

// output = [ '81', '82', '84', '01', '02', '04', '51', '52', '54', '71', '72', '74', '91', '92', '94' ];

vasanthv

const factorial = (n) => (Array.from(Array(n), (_, i) => i + 1)).reduce((a, b) => a * b);

vasanthv

//Based on https://stackoverflow.com/a/42531964

function combinations(array, length) {
    const arr = new Array(1 << array.length).fill().map(
        (e1, i) => array.filter((e2, j) => i & 1 << j));
    return length ? arr.filter(a => a.length == length) : arr;
}

//console.log(combinations([1, 2, 3, 8, 10], 2));

vasanthv

const random = (i,j) => (Math.floor(Math.random() * (j - i)) + i);

vasanthv

//Based on https://stackoverflow.com/a/46880431/607608

function getComb(set, val) {
    const res = [];
    function comb(set, k, partial, pref) {
        if (!partial) partial = [];
        for (const element in set) {
            if (k > 1) {
                const set_copy = set.slice();
                set_copy.splice(element, 1);

vasanthv

function getRandom(arr, n) {
    var result = new Array(n),
        len = arr.length,
        taken = new Array(len);
    if (n > len)
        throw new RangeError("getRandom: more elements taken than available");
    while (n--) {
        var x = Math.floor(Math.random() * len);
        result[n] = arr[x in taken ? taken[x] : x];
        taken[x] = --len in taken ? taken[len] : len;