Hello JavaScript code newbie! In this article I’m proposing you a series of coding challenges that will help you practice the basic language constructs and algorithms.

These coding challenges are intended for beginners, therefore the proposed solutions are implemented using only simple and classical programming elements. Each solution is accompanied by an online link that helps you quickly run it in a code playground at codeguppy.com

If you have time, we recommend you to solve the challenges on your own and then compare your solution to the provided solution. If time is limited, just browse through the solutions!

Note: The code is making use of the codeguppy specific function println() to print the results. If you want to run these solutions outside codeguppy.com, just replace println() with console.log() then run them using your browser console tool or node.js.

## Coding challenge #1: Print numbers from 1 to 10

https://codeguppy.com/code.html?mrgCtLGA90Ozr0Otrs5Z

``````for(var i = 1; i <= 10; i++)
{
println(i);
}
``````

## Coding challenge #2: Print the odd numbers less than 100

https://codeguppy.com/code.html?eDLA5XPp3bPxP79H2jKT

``````for(var i = 1; i <= 100; i += 2)
{
println(i);
}
``````

## Coding challenge #3: Print the multiplication table with 7

https://codeguppy.com/code.html?fpnQzIhnGUUmCUZy1fyQ

``````for(var i = 1; i <= 10; i++)
{
var row = "7 * " + i + " = " + 7 * i;
println(row);
}
``````

## Coding challenge #4: Print all the multiplication tables with numbers from 1 to 10

``````for(var i = 1; i <= 10; i++)
{
printTable(i);
println("");
}

function printTable(n)
{
for(var i = 1; i <= 10; i++)
{
var row = n + " * " + i + " = " + n * i;
println(row);
}
}
``````

## Coding challenge #5: Calculate the sum of numbers from 1 to 10

https://codeguppy.com/code.html?Vy6u9kki2hXM4YjsbpuN

``````var sum = 0;

for(var i = 1; i <= 10; i++)
{
sum += i;
}

println(sum);
``````

## Coding challenge #6: Calculate 10!

https://codeguppy.com/code.html?IIuJX4gnXOndNu0VrywA

``````var prod = 1;

for(var i = 1; i <= 10; i++)
{
prod *= i;
}

println(prod);
``````

## Coding challenge #7: Calculate the sum of odd numbers greater than 10 and less than 30

https://codeguppy.com/code.html?DcOffOyoIArmNZHVNM2u

``````var sum = 0;

for(var i = 11; i <= 30; i += 2)
{
sum += i;
}

println(sum);
``````

## Coding challenge #8: Create a function that will convert from Celsius to Fahrenheit

https://codeguppy.com/code.html?oI5mWm6QIMRjY1m9XAmI

``````function celsiusToFahrenheit(n)
{
return n * 1.8 + 32;
}

var r = celsiusToFahrenheit(20);
println(r);
``````

## Coding challenge #9: Create a function that will convert from Fahrenheit to Celsius

https://codeguppy.com/code.html?mhnf8DpPRqqgsBgbJNpz

``````function fahrenheitToCelsius(n)
{
return (n - 32) / 1.8;
}

var r = fahrenheitToCelsius(68);
println(r);
``````

## Coding challenge #10: Calculate the sum of numbers in an array of numbers

https://codeguppy.com/code.html?TteeVr0aj33ZyCLR685L

``````function sumArray(ar)
{
var sum = 0;

for(var i = 0; i < ar.length; i++)
{
sum += ar[i];
}

return sum;
}

var ar = [2, 3, -1, 5, 7, 9, 10, 15, 95];
var sum = sumArray(ar);
println(sum);
``````

## Coding challenge #11: Calculate the average of the numbers in an array of numbers

https://codeguppy.com/code.html?7i9sje6FuJsI44cuncLh

``````function averageArray(ar)
{
var n = ar.length;
var sum = 0;

for(var i = 0; i < n; i++)
{
sum += ar[i];
}

return sum / n;
}

var ar = [1, 3, 9, 15, 90];
var avg = averageArray(ar);

println("Average: ", avg);
``````

## Coding challenge #12: Create a function that receives an array of numbers and returns an array containing only the positive numbers

Solution 1:

https://codeguppy.com/code.html?0eztj1v6g7iQLzst3Id3

``````function getPositives(ar)
{
var ar2 = [];

for(var i = 0; i < ar.length; i++)
{
var el = ar[i];

if (el >= 0)
{
ar2.push(el);
}
}

return ar2;
}

var ar = [-5, 10, -3, 12, -9, 5, 90, 0, 1];
var ar2 = getPositives(ar);

println(ar2);
``````

## Coding challenge #12: Create a function that receives an array of numbers and returns an array containing only the positive numbers

Solution 2

https://codeguppy.com/code.html?KefrPtrvJeMpQyrB8V2D

``````function getPositives(ar)
{
var ar2 = [];

for(var el of ar)
{
if (el >= 0)
{
ar2.push(el);
}
}

return ar2;
}

var ar = [-5, 10, -3, 12, -9, 5, 90, 0, 1];
var ar2 = getPositives(ar);

println(ar2);
``````

## Coding challenge #12: Create a function that receives an array of numbers and returns an array containing only the positive numbers

Solution 3

https://codeguppy.com/code.html?qJBQubNA7z10n6pjYmB8

``````function getPositives(ar)
{
return ar.filter(el => el >= 0);
}

var ar = [-5, 10, -3, 12, -9, 5, 90, 0, 1];
var ar2 = getPositives(ar);
println(ar2);
``````

## Coding challenge #13: Find the maximum number in an array of numbers

https://codeguppy.com/code.html?THmQGgOMRUj6PSvEV8HD

``````function findMax(ar)
{
var max = ar[0];

for(var i = 0; i < ar.length; i++)
{
if (ar[i] > max)
{
max = ar[i];
}
}

return max;
}

var ar = [-5, 10, -3, 12, -9, 5, 90, 0, 1];
var max = findMax(ar);
println("Max: ", max);
``````

## Coding challenge #14: Print the first 10 Fibonacci numbers without recursion

https://codeguppy.com/code.html?rKOfPxHbVwxNWI2d8orH

``````var f0 = 0;
println(f0);

var f1 = 1;
println(f1);

for(var i = 2; i < 10; i++)
{
var fi = f1 + f0;
println(fi);

f0 = f1;
f1 = fi;
}
``````

## Coding challenge #15: Create a function that will find the nth Fibonacci number using recursion

https://codeguppy.com/code.html?IneuIg9O0rRV8V76omBk

``````function findFibonacci(n)
{
if (n == 0)
return 0;

if (n == 1)
return 1;

return findFibonacci(n - 1) + findFibonacci(n - 2);
}

var n = findFibonacci(10);
println(n);
``````

## Coding challenge #16: Create a function that will return a Boolean specifying if a number is prime

https://codeguppy.com/code.html?fRYsPEc2vcZTbIU8MKku

``````function isPrime(n)
{
if (n < 2)
return false;

if (n == 2)
return true;

var maxDiv = Math.sqrt(n);

for(var i = 2; i <= maxDiv; i++)
{
if (n % i == 0)
{
return false;
}
}

return true;
}

println(2, " is prime? ", isPrime(2));
println(3, " is prime? ", isPrime(3));
println(4, " is prime? ", isPrime(4));
println(5, " is prime? ", isPrime(5));
println(9, " is prime? ", isPrime(9));
``````

## Coding challenge #17: Calculate the sum of digits of a positive integer number

https://codeguppy.com/code.html?RHA714FYio8gWgmjWYPz

``````function sumDigits(n)
{
var s = n.toString();
var sum = 0;

for(var char of s)
{
var digit = parseInt(char);
sum += digit;
}

return sum;
}

var sum = sumDigits(1235231);
println("Sum: ", sum);
``````

#javascript #developer

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