Variables are containers for storing data (values).
In this example, x, y, and z, are variables, declared with the var keyword:
var x = 5;
var y = 6;
var z = x + y;
From the example above, you can expect:
x stores the value 5
y stores the value 6
z stores the value 11
var price1 = 5;
var price2 = 6;
var total = price1 + price2;
In programming, just like in algebra, we use variables (like price1) to hold values.
In programming, just like in algebra, we use variables in expressions (total = price1 + price2).
From the example above, you can calculate the total to be 11.
1.reserved keywords cannot be used as variable names
let function = 'fun'; //error as function cannot be a name
2.variable names can start with $ or underscores and alphabets
let$function = 3; // this is allowed
3.conventionally variables must not start with caps until its a
class or constant
let Person = 'Jonas';
4.constants are writtern with upper case
let PI = 3.1233;
5.naming conventions that involve elaborate wordings are prefered
over including numbers in the declaration.
let myFirstJob = "programmer"; let myCurrentJob = "teacher"; let country = "India"; let continent = "Asia"; let population = 565756767687; let job1="programmer"; let job2="teacher";
1.declaring a variable and assigning a value to the variable let js = 'amazing'; 2. console.log() is used whenever we need to output something to the browser console.log(40*8+23-10); console.log("Jonas"); console.log(23); let firstName = "Jonas"; //first_name notation isalso used console.log(firstName);
3.camel case is used when more than one words are used
let 3years=7;//variable name cannot start with a number let first_name ="aishwarya"; let jonas$natella ='JN'// error as we can have only numbers,letters,and underscores