basicJSExercises.js

/* ---------------------------
*** #1 Percentage ***

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

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

Output:
742.4
 --------------------------- */

function percentage(number, percentage) {
  var calculate = (number/100)*percentage;
  return calculate;
}
console.log("Percentage Calculator:");
/* Uncomment the following to check */
  console.log(percentage(2000, 37.12));
  console.log(percentage(450, 56.5));
  console.log(percentage(5230, 34));


/* ---------------------------
*** #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
 --------------------------- */

 function areaTriangle(base, height) {
   return base*height/2;
 }
 console.log("Triangle Area Calculator:");
 /* Uncomment the following to check */
    console.log(areaTriangle(2, 7));
    console.log(areaTriangle(20, 56.5));
    console.log(areaTriangle(50, 34));


/* ---------------------------
*** #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()
 --------------------------- */

function rotate_string(text) {
  console.log(text);
  for(var i=0;i<text.length;i++){
    text = text[text.length-1] + text.substring(0, text.length-1);
    console.log(text);
  }
}

console.log("Rotate String:");
/* Uncomment the following to check */
  rotate_string("cat");
  rotate_string("pseudonym")


/* ---------------------------
*** #4 Hide part of email address ***

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

Test:
console.log(protect_email("tom_jenkins@example.com"));

Output:
"tom_j...@example.com"

HINT: Use split() and substring()
 --------------------------- */

function protect_email(email) {
  var array = email.split('@');
  return array[0].substring(0,5) + "..." +'@'+array[1];
}

console.log("Protected email:");
/* Uncomment the following to check */
  console.log(protect_email("harry_potter@gmail.com"));
  console.log(protect_email("sarah.connor@gmail.com"));
  console.log(protect_email("tom_jenkins@example.com"));


/* ---------------------------
*** #5 Remove First Occurence ***

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()
 --------------------------- */

function remove_first_occurrence(text, searchstring) {
  text = text.slice(0,text.indexOf(searchstring)) + text.slice(text.indexOf(searchstring)+searchstring.length+1)
  return text;
}

console.log("Remove First Occurrence:");
/* Uncomment the following to check */
  console.log(remove_first_occurrence("The quick brown fox jumps over the lazy dog", 'the'));
  console.log(remove_first_occurrence("Drastic times call for drastic measures", 'drastic'));


/* ---------------------------
*** #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() functions
 --------------------------- */

function alphabetic_order(word) {
  return word.split("").sort().join("");
}

console.log("Alphabetic Order:");
/* Uncomment the following to check */
  console.log(alphabetic_order("textbook"));
  console.log(alphabetic_order("webmaster"));
  console.log(alphabetic_order("supercalifragilisticexpialidocious"));


/* ---------------------------
*** #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
 --------------------------- */

function most_frequent(arr) {
  var item;
  var max=0 ;
  var count = 0;
  for(var i=0;i<arr.length;i++){
    for(var j=i;j<arr.length;j++){
      if(arr[i]===arr[j]){
        count++;
      }
    }
    if(count>max){
      item = arr[i];
      max = count;
    }
    count = 0;
  }
  console.log(item + " occurs " + max + " times");
}

console.log("Most Frequent Item:");
/* Uncomment the following to check */
  most_frequent([3, 'c', 'c', 'c', 2, 3, 'c', 3, 'c', 2, 4, 9, 3]);
  most_frequent([7, 2, 'ax', '9', 9, 'ax', 'ax']);


/* ---------------------------
*** #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]
 --------------------------- */

function remove_duplicates(arr) {
  var duplicateRemoved = [];
  var isexists = false;

  for(var i=0;i<arr.length;i++){
    for(var j=0;j<duplicateRemoved.length;j++){
      if(arr[i]===duplicateRemoved[j]){
        isexists = true;
      }
    }
    if(!isexists){
      duplicateRemoved[duplicateRemoved.length]= arr[i];
    }
    isexists = false;
  }
  console.log(duplicateRemoved);
}

console.log("Remove Duplicate Values:");
/* Uncomment the following to check */
  remove_duplicates([3, 'a', 'a', 'a', 2, 3, 'a', 3, 'a', 2, 4, 9, 3]);
  remove_duplicates([4, 4, 4, 5, 's', 8, 's']);


/* ---------------------------
*** #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"
 --------------------------- */

function dash_in_even(number) {
  var str = "";
  number = number.toString();
  for(var i=0;i<number.length;i++){
    str = str + number[i];
    if(number[i]%2 == 0 && number[i+1]%2 == 0){
      str = str + '-';
    }
  }
  console.log(str);
}

console.log("Dash between Even Numbers:");
/* Uncomment the following to check */
  dash_in_even(100);
  dash_in_even(1356);
  dash_in_even(246824);
  dash_in_even(1324567824);


/* ---------------------------
*** #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()
 --------------------------- */

function guessing_game(guess) {
  var rand = Math.ceil(Math.random()*10);
  if(guess == rand){
    console.log("Good Work");
  }
  else{
    console.log("Not Matched");
  }

}

console.log("Guessing Game:");
/* Uncomment the following to check */
  var guess = prompt('Guess the number between 1 and 10 inclusive');
  console.log("User guessed: "+ guess);
  guessing_game(guess);