Module-18 Practice Section
Video 18-0: Basic Concepts of variable all in one
Video 18-1: Module Introduction and Variable recap
Two types of number : Integer: 120; float,/decimal 8.99;
Variable naming convension: rules, best practice:
1. single word
2. no gap or speace
3. no quote
4. no keyword
5. can not start with a number
6. can not contain dash
7. should use camelCase
Video 18-2 : Declare Array, array length and array index
Three things to write array: first [], gap then ,=⇒ var friendAge = [11, 23, 67, 87]; or var nayikas= [ ‘mahi’ ‘shabnur’ , ‘opu’];
console.log(array name.length)=⇒ number of array elements.==array position\ index starts from zero.
Video 18-3 : Array index, get and set by index, indexOf
var numbers = [45, 68, 78, 56, 89, 98];
//get element by index
console.log(numbers[0])=> to finf first element=>45
var element = numbers[1];
console.log(element); Result-68;
numbers[1] = 77;
numbers[3] = 44;
console.log(numbers); => [45, 77, 78,44, 89, 98];
Video 18-4 : Add or remove element from array using push, pop
var friend =[’balam’, ‘kalam’, ‘salam’];
friends.push(’galam’);
console.log(friends);
number.pop();=⇒ to remove last element from aray
Search google:
How to add a element of the beginning of array.
Search Google: How to add an element to an array of the beginning. and how to remove first element of an array of javascript
Video 18-5 Compare variables and Comparison operator
Video 18-6 Make conditional decision, if-else, comparison
var iphonePrice = 79000;
var myBudget = 9500;
// if iphone price is less than my budget, i will buy the phone
if(condition){
//will execute if the condition is true
}
if(chickenPrice < myMoney){
console.log('I will eat chicken');
}
else{
console.log('I will eat potato');
}
Video 18-7 Handle multiple conditions, and or
var isGraduated= true;
var salary - 60000;
if(isGraduated === true && salary > 50000){
console.log('Eso biye kore feli')
}
else{
console.log('tor kopale Biya nai')
}
if((isGraduated === true || salary > 50000) || cars>= 1){
console.log('Eso prem kori');
}
else{
console.log('Tumar kopale premnai')
}
Video 18-8 (advanced) Multi stage condition and nested conditionsr
var money = 10;
var danishPrice = 45;
var butterBread = 35;
var toastBiscute = 20;
if(danishPrice< money){
console.log('Dan den danish khamu');
}
else if (butterBread < money){
console.log('Butter bon khamu')
}
else if(toastBiscute < money){
console.log('Toast biscute khamu)
}
else('Khali cha khamu')
18-9 Module summary and two more comparison
- Array is a collection of similar data elements
- Array index indicates the position of the element within the array
- Array length is the total number of the elements in an array
- The indexOf() method returns the index (position) of a specified value.
- We van replace an element in an array with the help of array indices
- e.g arrayName[index] = newValue
- The push() method adds new items to the end of an array
- The pop() method removes the last element from the end of an array
QUIZ
Q1: What is the starting index of an array?
Ans: 0
Q2: What would be the index of “developer” in the array?
var dream = [“I”, “will”, “become”, “a”, “developer”, “inshallah”];
Ans: 4
Q3: How will you get the second element of the array arr = [3, 7, 10]?
Ans: arr[1]
Q4: What is the output of the following code snippet?
let myArray = [1, 2, 3, 4, 5];
console.log(myArray[2]);
Ans: 3
Q5: Which of the following array methods adds an element to the end of an array?
Ans: push
Q6: What is the output of the following code snippet?
let x = 5;
let y = 10;
if (x < y) {
console.log("x is less than y");
} else {
console.log("x is greater than or equal to y");
}
Ans: x is less than y
Q7S: What will be the output console.log(6 != 6);
Ans: false
Q8: What will be the output console.log(6 >= 6);
Ans: true
Q9: Where you don’t have to add a condition?
Ans: else
Q10: Which JavaScript array method removes and returns the last element of an array?
Ans: pop()
The End
var isGraduated= true;
var salary - 60000;
if(isGraduated === true && salary > 50000){
console.log('Eso biye kore feli')
}
else{
console.log('tor kopale Biya nai')
}
if((isGraduated === true || salary > 50000) || cars>= 1){
console.log('Eso prem kori');
}
else{
console.log('Tumar kopale premnai')
}
var money = 10;
var danishPrice = 45;
var butterBread = 35;
var toastBiscute = 20;
if(danishPrice< money){
console.log('Dan den danish khamu');
}
else if (butterBread < money){
console.log('Butter bon khamu')
}
else if(toastBiscute < money){
console.log('Toast biscute khamu)
}
else('Khali cha khamu')