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why does javascript have hoisting

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Smiling Starling answered on November 21, 2020 Popularity 10/10 Helpfulness 2/10

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why does javascript have hoisting

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// why does javascript have hoisting?

As Stoyan Stefanov explains in "JavaScript Patterns" book, the hoisting is 
result of JavaScript interpreter implementation.

The JS code interpretation is performed in two passes. 
a) During the first pass, the interpreter processes 
variable[NOT the initialitations] and function declarations.

b)The second pass is the actual code execution step. The interpreter processes 
function expressions and undeclared variables.

Thus, we can use the "hoisting" concept to describe such behavior.

Popularity 10/10 Helpfulness 2/10 Language javascript

Source: Grepper

Tags: hoisting javascript

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Contributed on Mar 03 2022

Smiling Starling

0 Answers Avg Quality 2/10

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js hoisting

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/*Hoisting is JavaScript's default behavior of moving 
all declarations to the top of the current scope (script or function).
Be carefull that only declaration gets hoisted NOT the initialitations*/

var x = 5;
alert("x is  = "+x+". y is = "+y);//result => x is = 5. y is = undefined.
var y = 7;

/*
note that the code doesn't produce the error "y is not defined" like
it would if we would omit y. It executes but not in the way you would want.
*/

Popularity 10/10 Helpfulness 4/10 Language javascript

Source: Grepper

Tags: hoisting hoistin

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Contributed on Nov 21 2020

CaligolaGG

0 Answers Avg Quality 2/10

javascript hoisting

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hoistedVariable = 3;
console.log(hoistedVariable); // outputs 3 even when the variable is declared after it is initialized	
var hoistedVariable;

Popularity 10/10 Helpfulness 3/10 Language javascript

Source: www.interviewbit.com

Tags: hoisting hoistin

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Contributed on Dec 17 2021

Grotesque Gorilla

0 Answers Avg Quality 2/10

hoisting in js

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Within the function, we first declare the name 
variable with the var keyword. This means that 
the variable gets hoisted (memory space is set 
up during the creation phase) with the default 
value of undefined, until we actually get to the 
line where we define the variable. We haven't defined
the variable yet on the line where we try to log the 
name variable, so it still holds the value of undefined.

Variables with the let keyword (and const) are hoisted,
but unlike var, don't get initialized. They are not
accessible before the line we declare (initialize) 
them. This is called the "temporal dead zone". When we 
try to access the variables before they are declared, 
JavaScript throws a ReferenceError.

function sayHi() {
  console.log(name);
  console.log(age);
  var name = 'Lydia';
  let age = 21;
}

sayHi();

Popularity 8/10 Helpfulness 3/10 Language javascript

Source: github.com

Tags: hoisting hoistin

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Contributed on Nov 29 2023

Imran Khan

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javascript hoisting

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/*
Hoisting in JavaScript is a behavior in which a function 
or a variable can be used before declaration
*/

// using test before declaring
console.log(test);   // undefined
var test;

Popularity 10/10 Helpfulness 2/10 Language javascript

Source: www.programiz.com

Tags: hoisting hoistin

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Contributed on Jun 17 2022

Rasel Ahmed

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function hoisting in js

Comment

console.log(functionBelow("Hello"));
var functionBelow = function(greet) {
   return `${greet} world`;
}
console.log(functionBelow("Hi"));

Popularity 10/10 Helpfulness 2/10 Language javascript

Source: www.tutorialspoint.com

Tags: function functio

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Contributed on Mar 03 2021

Yellowed Yak

0 Answers Avg Quality 2/10

function hoisting in js

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console.log(functionBelow("Hello"));
function functionBelow(greet) {
   return `${greet} world`;
}
console.log(functionBelow("Hi"));

Popularity 10/10 Helpfulness 2/10 Language javascript

Source: www.tutorialspoint.com

Tags: function functio

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Contributed on Mar 03 2021

Yellowed Yak

0 Answers Avg Quality 2/10

javascript Variable Hoisting

Comment

// program to display value
a = 5;
console.log(a);
var a; // 5

Popularity 9/10 Helpfulness 2/10 Language javascript

Source: Grepper

Tags: hoisting hoistin

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Contributed on May 21 2022

SAMER SAEID

0 Answers Avg Quality 2/10

hoisting in javascript

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// hoisting is as if your `function fun() {}` was located here. 

fun(); // works. 

function fun() {}

Popularity 10/10 Helpfulness 2/10 Language javascript

Source: fireship.io

Tags: hoisting hoistin

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Contributed on Feb 01 2022

madhav

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JavaScript Hoisting

Comment

x = 5; // Assign 5 to x

elem = document.getElementById("demo"); // Find an element
elem.innerHTML = x;                     // Display x in the element

var x; // Declare x

Popularity 10/10 Helpfulness 2/10 Language javascript

Source: Grepper

Tags: hoisting hoistin

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Contributed on May 23 2022

naly moslih

0 Answers Avg Quality 2/10

why does javascript have hoisting

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