JavaScript

JavaScript is a high-level, compiled language. It is dynamically typed It has application programming interfaces (APIs) for working with text, dates, regular expressions, standard data structures, and the Document Object Model (DOM).

variables

Three ways to create variables

1. var
2. let
3. const

var keyword:

var keyword is used when we need a variable to be declared or modified/updated. It can be played with outside the code-block too!

var a = "Hello"
var b = 1

We'll see about var keyword more!

let keyword:

let keyword is newly introduced in ECMASCRIPT2015/ES6. They are block scoped and the recommended way of declaring variables. unlike var it cannot be redeclared (within it's scope)

let a = "Hello"
let b = 10

const keyword:

const keyword is used when you don't need the value of the variable to change/update. const variables cannot be redeclared or updated, and it'll throw an error.

const a = "I ❤ JS"
const = 50

Conditionals:

1. if
2. if else
3. if else-if else
4. switch

if:

if (a<b){
  console.log("do this")
}

if else:

if (a<b){
  console.log("do this")
}
else {
  console.log("else do this")
}

if else-if else:

if (a<b){
  console.log("do this")
}
else if (a>b) {
  console.log("else do this")
}
else {
  console.log("else finally this")
}

switch:

switch(a<b) {
  case one:
    console.log("case 1 done ✔")
    break;
  case two:
    console.log("case 1 done ✔")
    break;
  default:
    console.log("default ✔")
} 

Loops:

1. for
2. while
3. do-while

for loop:

let a = 10
for (let i=0; i<a; i++){
  console.log("Hello")
}

while loop:

let a = 20;
let n = 0;
while (n < a) {
  console.log("Looping...")
  n++
}

do-while loop:

let a = 20;
let n = 0;
do {
    console.log("Looping...");
    n++
} while (n < a);

JS Objects:

Objects are a collection of properties in a single variable with preferably const declration. An Object can contain multiple properties

 const pen = {
              type:"ink", 
              model:"parker",
              color:"blue"
              };
 const anotherpen = {
                    type: "Gel",
                    model: "Trimax",
                    color: "black"
                    };

To access the properties of the JS Object we use . (dot) operator. Let us try to access one property of the above object

pen.type // ink
anotherpen.color // black
pen.model // parker
anotherpen.type // Gel

Functions:

function sampleGreet(name) {
  let Greet = "Hello"
  return Greet + " " + name + " 👋"
}
name = "GDSC"
sampleGreet(name)