Notice: This page requires JavaScript to function properly.
Please enable JavaScript in your browser settings or update your browser.Lära Var 2/3 | Data Types and Variables
Introduction to JavaScript

book
Var 2/3

Var Tolerate Redeclaration

Var tolerates the redeclaration. If a variable is declared with the same name twice with var we will not get an error, but with let we will get an error. For instance:

let user = 'Mike';
let user = 'John';

              
12

            
let user = 'Mike';
let user = 'John';
copy

But we can declare variables with the same names with var and the old values of the variables are simply overwritten, for example.

var user = 'Mike';
var user = 'John';
console.log(user)

              
123

            
var user = 'Mike';
var user = 'John';
console.log(user)
copy
Uppgift

Swipe to start coding

Declare a variable company and assign the value " Apple". Redeclare the company and now set the value “Samsung” by using the var keyword. Show the updated value on the console.

Lösning

var company="Apple";
var company="Samsung";
console.log(company);

Variable hoisting

Hoisting, in JavaScript, is a way where a function or a variable can be used before its declaration.
In JavaScript, var is hoisted while the let and const does not allow hoisting, for example.

totalNumber = 10;
console.log(totalNumber);
var totalNumber;

              
123

            
totalNumber = 10;
console.log(totalNumber);
var totalNumber;
copy

If we use the variable inside console.log() and nothing is written before it we will get an undefined value. In JavaScript first, the memory is allocated to the variable and initially, their values are undefined after this they are assigned some values.

console.log(company)
var company="panasonic";

              
12

            
console.log(company)
var company="panasonic";
copy

Var allt tydligt?

Hur kan vi förbättra det?

Tack för dina kommentarer!

Avsnitt 3. Kapitel 5
single

single


Fråga AI

expand

Fråga AI

ChatGPT

Fråga vad du vill eller prova någon av de föreslagna frågorna för att starta vårt samtal

some-alt