Basic JS Exercises

Exercise 1: Percentage

Write a JavaScript function to calculate the percentage (%) of a given number.

Test: console.log(percentage(2000, 37.12));

Output: 742.4

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Exercise 2: Area of Triangle

Write a JavaScript function to calculate the area of a triangle given the base and height.

Test: console.log(areaTriangle(5, 20));

Output: 50

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Exercise 3: Rotate String

Rotate a given string in the right direction by periodically removing one letter from the end of the string and attaching it to the front.

Test: rotateString("cat");

Output:

cat

tca

atc

cat

HINT: Use substring()

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Exercise 4: Hide part of email address

Write a JavaScript function to hide email addresses to protect from unauthorized user.

Test: console.log(protect_email("[email protected]"));

Output: "[email protected]"

HINT: Use split() and substring()

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Exercise 5: Remove First Occurrence

Write a JavaScript function to remove the first occurrence of a given 'search string' from a string.

Test: console.log(remove_first_occurrence("The quick brown fox jumps over the lazy dog", 'the'));

Output: "The quick brown fox jumps over lazy dog"

HINT: Use indexOf() and slice()

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Exercise 6: Alphabetical Order

Write a JavaScript function that returns a passed string with letters in alphabetical order.

Test: console.log(alphabetic_order('textbook'));

Output: bekoottx

HINT: Use join(), split() and sort()

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Exercise 7: Most Frequent Item

Write a JavaScript function to find the most frequent item in a given array.

Test: most_frequent([3, 'c', 'c', 'c', 2, 3, 'c', 3, 'c', 2, 4, 9, 3]);

Output: c occurs 5 times

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Exercise 8: Remove Duplicate Values

Write a JavaScript program to find and remove duplicate values in a JavaScript array.

Test: remove_duplicates([3, 'a', 'a', 'a', 2, 3, 'a', 3, 'a', 2, 4, 9, 3]);

Output: [3, 'a', 2, 4, 9]

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Exercise 9: Dash between Even Numbers

Write a JavaScript program which accepts a number as input and inserts dashes (-) between two consecutive even numbers.

Test: dash_in_even(012345684);

Output: "012-456-8-4"

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Exercise 10: Guessing Game

Write a JavaScript program where the program takes a random integer between 1 to 10, the user is then prompted to input a guess number. If the user input matches with guess number, the program will display a message "Good Work" otherwise display a message "Not matched"

HINT: Use Math.ceil() and Math.random()

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Source: w3resource