Aquí os dejo un código mío de ejemplo para empezar a aprender a usar variables de tipo básico en JavaScript.
Es recomendable copiar el código y ejecutarlo en un intérprete de JavaScript y, a continuación, realizar los cambios que consideremos oportunos para comprender el funcionamiento.
'use strict' // This is a comment /*
This is a comment
on multiple lines
*/ // VARIABLES
//
// A variable is a symbol that represents a quantity that may vary.
//
// $identifier = value; var age = 25 // The value 25 is assigned to variable age // BASIC DATA TYPES
var temperature = -3.82 // Number
var name = 'Nacho López' // String
var has_car = true // Boolean (only two values: true or false) // ARITHMETIC OPERATIONS WITH NUMBERS
var x = 5
var y = 2 var z = x + y // Addition. Result: 7.
z = x - y // Subtraction. Result: 3.
z = x * y // Multiplication. Result: 10.
z = x / y // Division. Result: 2.5.
z = x % y // Modulo (remainder of the integer division). Result: 1. z++ // Increase the value of z by 1. Result: 2.
z-- // Decrease the value of z by 1. Result: 1. z = 50 - x * 6 / -0.5 //
z = (50 - x) * 6 / -0.5 // The order of operations is as in mathematics
z = (50 - x * 6) / -0.5 // z = 2 * z + 3 // Remember: the symbol = assigns a value to the variable // BASIC OPERATIONS WITH STRINGS
var a = 'GNU/'
var b = 'Linux'
var c = a + b // Concatenation Result: 'GNU/Linux'.
c = a.repeat(3) // Repetition Result: 'GNU/GNU/GNU/'. // PRINT VARIABLES ON CONSOLE
console.log('Hello, world!') // Prints on console: Hello, world!
console.log(x) // Prints the variable x // You can print on console strings and variables
console.log('I have bought', x, 'oranges and', y, 'lemons.') // DATA TYPE CONVERSION
var height = '95.4'
console.log(typeof(height)) // Prints the current data type
height = Number(height) // Convert a string to number
console.log(typeof(height)) var altitude = -544.432
console.log(typeof(altitude))
altitude = String(altitude) // Convert a number to string
console.log(typeof(altitude)) read more
