JAVASCRIPT

javascript variable

var user_name = prompt("Please enter your name:", "Type here");
alert("Hello " + user_name);

javascript variables

// here are the ways to define variables
var x = "hi"; // for global variables
let x = "hi"; // for block-scoped variables
const x = "hi"; // for block-scoped variables which can not be reassigned

js variable

let x;
x = 102;

var javascript

var is a keyword to define the varible in js but as of es-6 we, use let and const keywords for the same

var js

var num = 1:

variables in js

var Hello = "World";
let bool = false;
const int = 8788;

variable javascript

//You can make a variable by using:
var variable-name = 'defenition of the variable';
// Or you can use
let variable-name = 'defenition of the variable';

variables javascript

var example = "hello";
document.write(example);// it will say hello when it runs

js variables

// JS Variables
var varExample = "var"; // var is use for variable in js the problem with it that it has complicated scope 
let letExample = "let"; // let is pretty much same as var the only thing which make its more varriable is its variable scope.
const constExample = "const"; // const is use for constant values and this variable scope is sane as let

javascript variable

// This is best way to make a variable
// Varibales Store Data
var variable1 = 56;
//OR
var variable2 = true;

var variable3 = "Hello World";

var in js

I love you

js variables

// let & var are both editable variables:
var cow = 'moo';
let pig = 'oink';
cow = 10;
pig = 10;
// const is a permanent variable; you cannot change it.
const uncuttableGrass = '//';
uncuttableGrass = '___';
// above throws an error

js variables

//Making variables with let:
let numberOfFriends = 1;

//Incrementing:
numberOfFriends += 3; //numberOfFriends is now 4

// Variables with const
const minimumAge = 21; //CANNOT REASSIGN!

//Booleans - true or false values
true;
false;
let isHappy = true;

//Naming Conventions
// Use upper camel-cased names:
let numberOfChickens = 6; //GOOD
// NOT THE JS WAY:
// let number_of_chickens = 6;

javascript variables

// Also let, const
var e_number = 0;
var e_string = '';
var e_true = true;
var e_false = false;
var e_undefined = undefined;

JavaScript variables

let x = "Hello JavaScript";

let x = 0;

// SyntaxError: 'x' has already been declared

js var

function x() {
  y = 1;   // Genera un ReferenceError in strict mode
  var z = 2;
}

x();

console.log(y); // scrive "1" in console
console.log(z); // Genera un ReferenceError: z non è definita fuori dalla funzione x

js var

var x = y, y = 'A';
console.log(x + y); // non definito

js variables

// Can be a number
var myVar = 21
//Can be a string
var myVar2 = "string"
// Used in a function
function printVar(parvar) {
  print(parvar);
}

printVar(myVar2);
// prints "string"
printVar(myVar);
// prints 21

js variables

// 3 ways to create

var mrVariable = 'x'; // You can set it to to a string ( '' ) or no. ( 0 ). It 
// is globally defined

let myVariaible2 = 'y'; // You can set it to string or no. let is block scoped

const myVariable = 'z'; // It is block scoped, can be a string or no. and can't 
//be reassigned

js var

var a = 'A';
var b = a;

// è come dire:

var a, b = a = 'A';

var = {} js

//An array is a type of object intended to be only assigned numeric keys
var tmp = []; // or: var tmp = {}
tmp.one = 1;
JSON.stringify(tmp);

// array:
'[]'

// object:
'{"one":1}'

javascript variable

var myString = "string"; //var can be redefined
var myInt = 34; //var can be redefined
const myString2 = "string"; //const cannot be redefined
const myInt2 = 69; //const cannot be redefined

js var

use let instead of var !!!

var js

var variable = "title"
console.log(variable)
//it should print aout the value of the variable 'variable'

Variables javaScript

let x = null;
let name = "Tammy";
const found = false;

// => Tammy, false, null
console.log(name, found, x);

var a;
console.log(a); // => undefined

JavaScript variables

let x = "Hello JavaScript";

let x = 0;

// SyntaxError: 'x' has already been declared

javascript variable

var variable = "Hello World";

js var

var a = 0, b = 0;

js var

var a = 1;
b = 2;

delete this.a; // Genera un TypeError in strict mode. Altrimenti fallisce senza generare messaggi.
delete this.b;

console.log(a, b); // Genera un ReferenceError.
// La proprietà 'b' è stata cancellata e non esiste più.

js var

console.log(a);                // Genera un ReferenceError.
console.log('still going...'); // Non verrà eseguito.

js var

var nomevariabile1 [= valore1] [, nomevariabile2 [= valore2] ... [, nomevariabileN [= valoreN]]];

js var

var x = 0;

function f() {
  var x = y = 1; // x è dichiarata localmente. y invece no!
}
f();

console.log(x, y); // Genera un ReferenceError in strict mode (y non è definita). 0, 1 altrimenti.
// In modalità non-strict mode:
// x è la globale come si ci aspettava
// però, y è uscita fuori dalla funzione!

js var

var a;
console.log(a);                // scrive in console "undefined" o "" a seconda del browser usato.
console.log('still going...'); // scrive in console "still going...".

var javascript

 var text = "";
var i;
for (i = 0; i < 5; i++) {
  text += "The number is " + i + "<br>";
} 

vars javascript

var /*var*/ = /*What it does*/

javascript variables

var a;                          // variable
var b = "init";                 // string
var c = "Hi" + " " + "Joe";     // = "Hi Joe"
var d = 1 + 2 + "3";            // = "33"
var e = [2,3,5,8];              // array
var f = false;                  // boolean
var g = /()/;                   // RegEx
var h = function(){};           // function object
const PI = 3.14;                // constant
var a = 1, b = 2, c = a + b;    // one line
let z = 'zzz';                  // block scope local variable

js var

var x = 0;  // x è dichiarata dentro l'ambiente file, poi le è assegnato valore 0

console.log(typeof z); // undefined, poichè z ancora non esiste

function a() { // quando a è chiamata,
  var y = 2;   // y è dichiarata dentro l'ambiente della funzione a, e le è assegnato valore 2

  console.log(x, y);   // 0 2

  function b() {       // quando b è chiamata
    x = 3;  // assegna 3 all'esistente ambiente x, non crea una nuova variabile globale
    y = 4;  // assegna 4 all'esistente esterna y, non crea una nuova variabile globale
    z = 5;  // crea una nuova variabile globale z e le assegna valore 5.
  }         // (Throws a ReferenceError in strict mode.)

  b();     // chiamare b crea z come variabile globale
  console.log(x, y, z);  // 3 4 5
}

a();                   // chiamando a si richiama b
console.log(x, z);     // 3 5
console.log(typeof y); // non definito, perchè y è locale alla funzione a