#Day2 Conditional Statements

#202124 Darcula theme color
if, else if, and else statements.
**********************************************
comparison operators.

Less than: <
Greater than: >
Less than or equal to: <=
Greater than or equal to: >=
Is equal to: ===
Is NOT equal to: !==
**********************************************
logical operators.
There are three logical operators:

the and operator (&&)
the or operator (||)
the not operator, otherwise known as the bang operator (!)
****************************************************************
truthy vs falsy values.

these values are false values when they are checked as a condition.
0
Empty strings like "" or ''
null which represents when there is no value at all
undefined which represent when a declared variable lacks a value
NaN, or Not a Number


|| it gets the value from left side
&& it gets the vaue from right side.
let tool = 'marker';

// Use short circuit evaluation to assign writingUtensil variable below:
let writingUtensil =tool || "pen";

console.log(`The ${writingUtensil} is mightier than the sword.`);

**********************************************
***ternary operators.***
Normal if else
let isLocked = false;

if (isLocked) {
console.log('You will need a key to open the door.');
} else {
console.log('You will not need a key to open the door.');
}
***ternary if else****
let isLocked = false;

isLocked ?
console.log('You will need a key to open the door.'):
console.log('You will not need a key to open the door.');



**********************************************
the switch statement.

this is an alternative of if-else statement.

because suppose if you want to check 100 of condition then it will be a pain to write that amount of conditions.
that's why we use SWITH CASE.

EXAMPLE :
let athleteFinalPosition = 'third place';
switch(athleteFinalPosition){
case "first place":
console.log('lo');
break;

case "third place":
console.log('third place prints');
break;

case "second place":
console.log('second place prints');
break;
default:
console.log("you loose");
}

if you wil not use break; keyword all the code blocks will run.
you should add break keyoword at the end of the default case
**********************************************

CONDITIONAL STATEMENTS
Review
Way to go! Here are some of the major concepts for conditionals:

An if statement checks a condition and will execute a task if that condition evaluates to true.
if...else statements make binary decisions and execute different code blocks based on a provided condition.
We can add more conditions using else if statements.
Comparison operators, including <, >, <=, >=, ===, and !== can compare two values.
The logical and operator, &&, or “and”, checks if both provided expressions are truthy.
The logical operator ||, or “or”, checks if either provided expression is truthy.
The bang operator, !, switches the truthiness and falseness of a value.
The ternary operator is shorthand to simplify concise if...else statements.
A switch statement can be used to simplify the process of writing multiple else if statements. The break keyword stops the remaining cases from being checked and executed in a switch statement.

you can reffer this for in depth knowladge

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Let Vs Var

diff between var and Let
the diff is scope

let has an inner scope
var is used to declare a global variable

// let b = "rahul";
for(let b=1;b<11;b++){
console.log(b);
}
console.log("b is:"+b);

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#day1 Javascript Variable

#Day1 #BackToBasics
1) const and Let Keywords are introduced in Es6 2015.

2) LET : LET has a Block Scope
VAR : VAR has a Function Scope

Let: it signals that variable can be assigned reassigned a different value
(it means let can be reassigned).
eg:- let meal = 'Enchiladas';
console.log(meal); // Output: Enchiladas
meal = 'Burrito';
console.log(meal); // Output: Burrito

3) if we don't assign a value to a variable it will give an output of undefined.

4) Const: const was introduced in es6 it is constant. if you try to redefine const variable it will give you TypeError: Assignment to constant variable.

5) constant variables need to assign a value at the time of declaration and if you don't assign a value it will give you SyntaxError.

6) Mathematical Operators
7) +=,
8) -=
9) *=
10) /=

11) String Interpolation : it can be done with `` this BackTics.
eg:- const myPet = 'armadillo';
console.log(`I own a pet ${myPet}.`);

12) Typeof operator: return the typeof variables (string, num, etc...)


Let’s review what we learned:

• Variables hold reusable data in a program and associate it with a name.
• Variables are stored in memory.
• The var keyword is used in pre-ES6 versions of JS.
• let is the preferred way to declare a variable when it can be reassigned, and const is the preferred way to declare a variable with a constant value.
• Variables that have not been initialized store the primitive data type undefined.
• Mathematical assignment operators make it easy to calculate a new value and assign it to the same variable.
• The + operator is used to concatenate strings including string values held in variables
• In ES6, template literals use backticks ` and ${} to interpolate values into a string.
• The typeof keyword returns the data type (as a string) of a value.

Apply your learning with Projects based on Javascript Variables.do it now

1) Kelvin Project
2) Dog Years

Learn More here

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