Variables and statements

Semicolons used to end a statement. You can choose to not write them (because there is ASI: Automatic Semicolon Insertion in Javascript).

Declaring a variable:

varfirst = 'Soumya';

letfirst = 'Soumya';

constfirst = 'Soumya';

(here value is 'Soumya')

let and const were introduced in ES6 (newer).

var and let can be updated but not const.

var x = 'hey';
y = 'hi';

let cool = true;
cool = false;

const age = 10;
age = 11; // wrong: throws error

In strict mode, we have to define a variable first before assigning a value to it.

dog = 'snickers'; // bad coding, don't do this
console.log(dog); // snickers (no error) 

'use strict';
dog = 'snickers'; // error: dog is not defined

If we write var dog; dog is undefined.

Scoping:

- var : function scoped (only available inside parent functions)

- let and const : block scoped (available inside a block denoted by { } )

Opinion (what to use): Use const by default; if the value of the variable needs to change then use let. Almost never use var.

Variable naming conventions:

Should not start with capital unless they are a class.
Must start with a-z or _ or $.
If a variable is multi-word, you can use:

Camel-case: let iLovePizza = true;
Upper Camel case (in case of classes): ILovePizza
Snake case: let i_love_pizza=true;