Basics of js; variable, operations, loops, arrays

basic_js.js

// Variables
var a = 1; 
let b = 2; 
const c = 3; 
const pi = 3.17;
console.log(a, b, c, pi);

// Operations
let sum = a + b;
let sub = a - b; 
let div = a / b;
let mutl = a * b;
let mod = a % b;

// Conditions

// if, else, elif, else if
if (a > b) {
  console.log('a is greater than b');
}else {
  console.log('a is not greater than b');
}

if (a == 2) {
  console.log('a is equalt to 2');
}else if(a == 4) {
  console.log('a is 4')
}else {
  console.log('a is neither 2 nor 4');
}

// switch
switch(a){
  case 2: 
      console.log('In case 2');
      break; 
  case 4: 
    console.log('In case 4');
    break;
  default: 
     console.log('in default')
}

// Loops
for($i = 0; $i <= 10; $i++) {
  console.log('ForLoop ' + $i);
}

$age = 0; 
while ($age <= 5) {
  console.log('I am a child ' + $age + ' years');
  $age++;
}

// Arrays
let names = ['john', 'peter', 'samuel'];
let familyArray = names.map((name, key) => {
  if (name == 'john') {
    return name;
  }else {
    let newName = name + ' ' + 'Ndelli'; 
    return newName; 
  }
});

console.log(familyArray);

// Functions
function sumFxn(a, b) {
  return a + b;
}

let sumFunctionReturnValue = sumFxn(1, 5);
console.log('My sum function returned ' + sumFunctionReturnValue);

// Objects
let student = {
  id: 1,
  name: 'Ndelli Peter', 
  class: 'DR Intern 1', 
  subject: 'Javascript',
  learn: function(){
    console.log('I am learning');
  }, 
  changeName: function(newName) {
    this.name = newName; 
  }, 
  setMark: function(mark) {
    this.mark = mark;
  }
}

console.clear();

// student.learn();
// console.log(student.name);
console.log(student);
student.changeName('Martin');
student.setMark(44);
console.log(student);