Complex

Spiral output for array

var m = [
  [0,  1,  2,  3,  4],
  [5,  6,  7,  8,  9],
  [10, 11, 12, 13, 14],
  [15, 16, 17, 18, 19]
];

var spiral = function (m) {
 // Put your code here
};

Should be [0, 1, 2, 3, 4, 9, 14, 19, 18, 17, 16, 15, 10, 5, 6, 7, 8, 13, 12, 11]

Sort array with semver-rules

var arr = [ "1.0.5", "2.5.0", "0.12.0", "1", "1.23.45", "1.4.50", "1.2.3.4.5.6.7"];

function semverSor() {
  // put your code here
}

semverSor(arr);

Like [ "0.12.0", "1", "1.0.5", "1.2.3.4.5.6.7", "1.4.50", "1.23.45", "2.5.0" ]

Implement deepClone ( withour recursive links and functions Simpliest , suppose is JSON.parse(JSON.stringify(m)) but we need real code =)

Implement bind(func, context). Make polyfill .bind(context)

Check if string is anagramm ( start-to-end is the same as end-to-start) Like ololo. Option -- the same without spaces like olo lo Option - the same in functional style

We have next stub Fill blank methods to describe algorithms for servicing multistory building with your elevator. You have only low-leve intarface (HardwareElevator) with three states - stoppes, move up, move down. Every floor has two buttons up/down Inside cabin there are only buttons with numbers

DIRECTION_DOWN = -1
DIRECTION_NONE = 0
DIRECTION_UP = 1

function HardwareElevator(){};
HardwareElevator.prototype = {
    moveUp:function(){console.log('moving up');},
    moveDown:function(){console.log('moving down');},
    stopAndOpenDoors:function(){console.log('stopping and opening doors');},
    getCurrentFloor:function(){console.log('getting current floor');},
    getCurrentDirection:function(){console.log('getting current drection');}
}

function Elevator() {
    this.hw = new HardwareElevator();
    this.hw.addEventListener("doorsClosed", _bind(this.onDoorsClosed, this));
    this.hw.addEventListener("beforeFloor", _bind(this.onBeforeFloor, this));
}
Elevator.prototype = {
    onDoorsClosed: function(floor) {
      // put your code here
    },
    onBeforeFloor: function(floor, direction) {
      // put your code here
    },
    floorButtonPressed: function(floor, direction) {
      // put your code here
    },
    cabinButtonPressed: function(floor) {
      // put your code here
    }
}

Implement chain map-method which can work with async functions ( promises-based ) Like:

Chain([link1,link2,link3]).mapAsync(link => get(link)).mampAsync(page => printPage)

Write code which will output itself into console/document

We want to write calculations using functions and get the results. Let's have a look at some examples:

seven(times(five())); // must return 35
four(plus(nine())); // must return 13
eight(minus(three())); // must return 5
six(dividedBy(two())); // must return 3

Requirements:

There must be a function for each number from 0 ("zero") to 9 ("nine")
There must be a function for each of the following mathematical operations: plus, minus, times, dividedBy (divided_by in Ruby)
Each calculation consist of exactly one operation and two numbers
The most outer function represents the left operand, the most inner function represents the right operand

Написать функцию котороя будет разворачивать буквы в словах предложения, но только лишь буквы цифры и специальные символы должны остаться на месте

<!-- prettier-ignore-end -->
// s1tar3t 2 hellow  ->  t1rat3s 2 wolleh
// s1ta$%r3t 2 hel^low  ->  t1ra$%t3s 2 wol^leh
// s1tar3t 2   low5  ->  t1rat3s 2   wol5

Реализовать фукнционал, допускающий следующий код

(3).add(5).multiply(2) // 16

Нужно реализовать следующие методы

add
subtract
multiply
divide
square
После должна появится возможность выстраивать команды в цепочку ( см пример выше )

Implement simple module system with injection system like in angular

function($moduleName, $anotherModuleName){}

should get objects from module('moduleName') / module(anotherModuleName)

Output?

var f = (function f(){ return "1"; }, function g(){ return 2; })();
typeof f;

Output?

var text = 'outside';
function logIt(){
    console.log(text);
    var text = 'inside';
};
logIt();

Game where everyone win. Output?

<button id="btn-0">Button 1!</button>
<button id="btn-1">Button 2!</button>
<button id="btn-2">Button 3!</button>
<script type="text/javascript">
    var prizes = ['A Unicorn!', 'A Hug!', 'Fresh Laundry!'];
    for (var btnNum = 0; btnNum < prizes.length; btnNum++) {
        // for each of our buttons, when the user clicks it...
        document.getElementById('btn-' + btnNum).onclick = function() {
            // tell her what she's won!
            alert(prizes[btnNum]);
        };
    }
</script>

Define a spacify function which takes a string as an argument, and returns the same string but with each character separated by a space

spacify('hello world') // => 'h e l l o w o r l d'
'hello world'.spacify() // => 'h e l l o w o r l d'

Write a program that prints all the numbers from 1 to 100. For multiples of 3, instead of the number, print "Fizz", for multiples of 5 print "Buzz". For numbers which are multiples of both 3 and 5, print "FizzBuzz".

Option: do it without conditional statements (if/switch/?:) Option: do not use logical operators (&& / ||) Option: do not use loops (for/do/while/etc)

Create lazy-evaluations POC

var le = new LazyEval([1, 2, 3, 4, 5])
  .filter(i => i > 2)
  .map(i => i * 2);
le.value(); // [6, 8, 10]

BUT! all evaluations should be done only after .value() call

Create .bind method for function without using .call/.apply (only trash, only hardcore)

Create compose function

const compose = (f1, f2) => value => f1( f2(value) )

list of functions can has any length
for zero-length list it should return () => undefined compose(fn, fn1, fn2, fn3) ... etc

Implement .map using .reduce for iteration ( for arrays )

Fnd average age for male-users

var users = {
  'Bob': { age: 24, isMale: true },
  'Sam': { age: 23, isMale: true },
  'Mag': { age: 54, isMale: false },
  'Ken': { age: 43, isMale: true },
  'Marta': { age: 34, isMale: false },
  'Duglas': { age: 27, isMale: true },
  'Martin': { age: 34, isMale: true },
};

Challenge: Implement a tic-tac-toe game (3x3)

Requirements:

program must be a pure JavaScript solution. not looking for a web application here
program must play a game for both players with no user interaction
program must display the game board after each player move
program must display the game winner, or 'draw' if not won

Notes:

program does not have to choose a player move intelligently
don't bother drawing lines for the game board
feel free to use underscore/lodash if you like
feel free to use es6/es2015 features if you like

Begin when ready, and remember to verbalize your design and implementation thoughts as you proceed.

About promises:

Suppose findData is a function that takes a query object and returns a promise for the result of the query.
Suppose also that someRandomArrayOfQueries is an array of query objects.

Explain what would be printed by the following code and why

function runMultipleQueries(queries) {
 var results = [];
 queries.forEach(doQuery);
 return results;

 function doQuery(query) {
   findData(query)
   .then(results.push.bind(results));
 } 
}
function log(value) {
 console.log(value);
}
runMultipleQueries(someRandomArrayOfQueries).forEach(log);

Create code to pass test ( mocha, but it doesn't metter )

describe('Step 5', function() {
  it('add(2,8)(5).value() => 15', function() {
    add(2,8)(5).value()
      .should.be.exactly(15).and.be.a.Number;
  });
  it('add(3, 3, 5)(4)(3, 2).value() => 20', function() {
    add(3, 3, 5)(4)(3, 2).value()
      .should.be.exactly(20).and.be.a.Number;
  });
});

Given two identical DOM trees (not the same one), and a node from one of them find the node in the other one.

What is the difference between these four promises?

doSomething().then(function () {
  return doSomethingElse();
});

doSomething().then(function () {
  doSomethingElse();
});

doSomething().then(doSomethingElse());

doSomething().then(doSomethingElse);

Implement function to remove duplication from list (array)

You have a function rand7() that generates a random integer from 1 to 7. Use it to write a function rand5() that generates a random integer from 1 to 5.

rand7() returns each integer with equal probability.
rand5() must also return each integer with equal probability.

For next markup

<div id="selectio">Select me!</div>

create js code ( via native js ) which on click at div will select all text inside note - just check range/selection api

A polindromic number reads the same both ways. The largest polindrome made from the product of two 2-digit numbers is 9009 = 91*99. Find the largest polindrom made from the product of two 3-digit numbers.

Given an input string, you should check if the string contains the same amount of 'x' and 'o'. The case doesn't matter - if the amount is equal, return a true otherwise return false.

describe('sameXOAmount()', () => {
   it('should return `true` if number of `X` and `O` is equal', () => {
     expect(sameXOAmount('xXoO')).toEqual(true);
     expect(sameXOAmount('aAxXXbBoOo')).toEqual(true);
     expect(sameXOAmount('abc')).toEqual(true);
    });
   it('should return `false` if number of `X` and `O` is not equal', () => {
    expect(sameXOAmount('OaAxXbBoO')).toEqual(false);
    expect(sameXOAmount('xgXoXsdxOxz')).toEqual(false);
    expect(sameXOAmount('aaAmmMxMM')).toEqual(false);
   });
 });

Given an array of numbers, you should find the number which occurs an odd number of times within the array. You can assume that there is always just one number with an odd amount. Furthermore the array is never undefined and contains only numbers.

describe('findOddAmount()', () => {
  it('should return the number which occurs with an odd frequency', () => {
     expect(findOddAmount([1, 2, 2, 3, 3])).toEqual(1);
     expect(findOddAmount([8, 8, 7, 7, 7])).toEqual(7);
     expect(findOddAmount([10, 3, 3, 10, 6, 10, 6, 1, 1])).toEqual(10);
   });
});

Create uniq function, witch takes a list and returns only uniq values from list. Like in lodash/underscore

Let imaging sequence 1010010001000010000010000001... (k(1->oo) "1{0xk}". Create function which takes number of symbols as an argument and returns n-first symbols of the sequence

Create .bind polyfill without using .call/.apply ( really tricky task, but it gives food for dicussion )

Based on list of chars, find the longes polindrome ( string equal in both directions: rtl = ltr ) like ['a', 'b', 'c', 'a', 'b', 'd'] => 'abcba' / 'abdba'

Implement shuffle(list) function which suffle list ( randomize list elements )

Create Promise implementation

NB: In fact it was pair programmng session but it could be meditative task, wich takes as much time as you have. It covers a lot of topics - async / flow / thenable-interface / functions / exceptions etc.

ar arr = [1,2,42,3];
var brr = [];

for (var i = 0; i < arr.length; i++) {
  if (arr[i] === 42) {
    // fill it as short as possible
    // to get brr equal to [1,2,3]
  }

  brr.push(arr[i]);
}

Write a matchSum(list, targetValue) function. Which takes list of numbers and target sum and returns pair of elements which gives target sum.

<!-- prettier-ignore-end -->
matchSum([4, 7, 1, 8, 9], 11); // [4, 7]

what if you need return all pairs?
could you implement linear complexity ?

Write your out trim() function (obviously - do not use String.prototype.trim). Extended: create trim('zxc') function which takes list of symbols to trim.

Are you familiar with common.js modules? When inside module we are able to use module / exports ? ( what's the difference in usage module.exports / exports ?) ) Please implement your own require function with the same functionality, as original.

Light version: Write a function checking that the given string is valid. We consider a string to be valid if all the characters of the string have exactly the same frequency.

Examples:

aabbcc is a valid string
aabbccc is an invalid string

Extended version: Check if the string is valid as it is (same condition as before) or if one character at one position can be removed from the string so it will become valid.

Examples:

aabbcc -> true
aabbcccc -> false
aabbccf -> true
aaabbbcccf -> true
aabbccc -> true
abcddff -> false
abcdefffff -> false
aabbccddd -> true

Again about brackets.

Easy part:

'(', '{', '[' are called "openers".
')', '}', ']' are called "closers". Write an efficient function that tells us whether input string's openers and closers are properly nested.

Examples:

<!-- prettier-ignore-end -->
"{ [ ] ( ) }" -> true
"{ [ ( ] ) }" -> false
"{ [ }" -> false
"class Example { public do() { return; } }" -> true
"class Example { public do( { return; } }" -> false

Extra: handle also next types of brackes

<!-- prettier-ignore-end -->
<>
''
||

There might be multiple ways how to interpret lines '''' ('('')' or ('')('')) - in my concrete situation we agreed that we're closing bracket everytime we can. It influences to the cases like '"'||'"' which we interpret like '("('(||)')")'

Tests we agreed during an interview:

test('', true);
test('some', true);
test('(', false);
test('()', true);
test('()[', false);
test('()[]', true);
test(')', false);
test('([)]', false);
test('((', false);
test('())', false);

test('class Example { public do() { return; } }', true);
test('class Example { public do( { return; } }', false);

test("('['", false); 
test("(')'", false);
test('("("[]")")', true);
test("(')'", false);
test("'||'''", true)

Your task is to embed a third-party video player library called SimplePlayer into your application. Here is an extract from the SimplePlayer API documentation:

<!-- prettier-ignore-end -->
CLASS:
   SimplePlayer

CONSTRUCTOR:
   new SimplePlayer(manifestUri)
       where manifestUri is the URI of video stream manifest

METHODS:
   play()
       initiate playback of video stream
   pause()
       pause playback of video stream
   getPlaybackStatus()
       get the playback status of the current video stream, returns a
       one of the following strings: "PLAYING", "STOPPED" or "BUFFERING"
   addPlaybackStatusListener(callback)
       allows a callback to be set that is executed whenever
       the playback status changes. The playback status ("PLAYING", "STOPPED"
       or "BUFFERING") is passed to the callback as the only argument.

QUESTIONS:

Create a basic test application in your chosen programming language that performs the following functions:

a) creates an instance of SimplePlayer

b) invokes the play command

c) logs the playback status to the console
Extend the code you have written with a "bufferMonitor" function which prints "too much buffering" to the console when the player is buffering continuously for more than one minute
If necessary refactor your code so that it is possible to unit test the bufferMonitor function (without mocking of setTimeout via testing frameworks and using of fake timers), then write appropriate unit tests.

Given a string S consisting of lowercase English characters determine if you can make it a palindrome by removing at most 1 character.

<!-- prettier-ignore-end -->
tacocats -> tacocat
racercar -> racecar or racrcar
kbayak -> kayak
acbccba -> abccba
abccbca -> abccba

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Complex

Write code which will output itself into console/document

Option: do it without conditional statements (if/switch/?:) Option: do not use logical operators (&& / ||) Option: do not use loops (for/do/while/etc)

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Complex

Write code which will output itself into console/document

Option: do it without conditional statements (if/switch/?:) Option: do not use logical operators (&& / ||) Option: do not use loops (for/do/while/etc)