JavaScript Hoisting and Variable Declarations Quiz

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Question 1/7

Consider this code: Which value will be logged to the console? 
var x = 1;
function testHoist() {
    console.log(y);
    var y = 5;
}
testHoist();

Select your answer

Question 2/7

What is the output of the following JavaScript code snippet? 
console.log(a);
var a = 10;
console.log(b);
let b = 20;

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Question 3/7

Which statement about variable hoisting in JavaScript is true?

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Question 4/7

Which of the following correctly illustrates variable hoisting with 'var'?

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Question 5/7

What will be the output of the code below? 
console.log(foo);
var foo = function() {
    return "Hello";
};

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Question 6/7

What will be the output of the following code? 
console.log(typeof myVar);
var myVar = 42;

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Question 7/7

Which variable declaration will throw a ReferenceError if accessed before initialization?

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Your Answers

Question 1/7
😊 Your answer was correct 🙁 Your answer was incorrect
Consider this code: Which value will be logged to the console? 
var x = 1;
function testHoist() {
    console.log(y);
    var y = 5;
}
testHoist();

Available answers

Inside the 
testHoist
function, the variable 
y
is declared with 
var
. Because 
var
is hoisted, the declaration is processed at the top of the function scope, but the assignment 
y = 5
is not, so it logs 
undefined
.
Question 2/7
😊 Your answer was correct 🙁 Your answer was incorrect
What is the output of the following JavaScript code snippet? 
console.log(a);
var a = 10;
console.log(b);
let b = 20;

Available answers

var a
is hoisted, so the initial 
console.log(a)
evaluates to 
undefined
. After the assignment 
a = 10
, the second 
console.log(a)
outputs 
10
. 
let b
is not hoisted, so 
console.log(b)
before its declaration results in a 
ReferenceError
.
Question 3/7
😊 Your answer was correct 🙁 Your answer was incorrect
Which statement about variable hoisting in JavaScript is true?

Available answers

Only the declarations of variables declared with 
var
are hoisted to the top of their function or global scope. Functions declared using function declarations (not expressions) are hoisted with their definitions, but 
let
and 
const
variables are hoisted in a manner that prevents access before the line of code they are defined on.
Question 4/7
😊 Your answer was correct 🙁 Your answer was incorrect
Which of the following correctly illustrates variable hoisting with 'var'?

Available answers

In the 
var
declaration, the variable 
a
is hoisted to the top of its scope as an undefined variable. However, the proper illustration of hoisting explicitly declares 
var a;
before it is used.
Question 5/7
😊 Your answer was correct 🙁 Your answer was incorrect
What will be the output of the code below? 
console.log(foo);
var foo = function() {
    return "Hello";
};

Available answers

The variable 
foo
is declared using 
var
, so it is hoisted to the top of the scope with an initial value of 
undefined
. Therefore, 
console.log(foo)
outputs 
undefined
because the function expression hasn't been evaluated yet.
Question 6/7
😊 Your answer was correct 🙁 Your answer was incorrect
What will be the output of the following code? 
console.log(typeof myVar);
var myVar = 42;

Available answers

The 
typeof
operator will return 
undefined
because 
myVar
is hoisted but not initialized at the time of the 
console.log
.
Question 7/7
😊 Your answer was correct 🙁 Your answer was incorrect
Which variable declaration will throw a ReferenceError if accessed before initialization?

Available answers

Variables declared with 
let
and 
const
are not hoisted in the traditional sense and will throw a 
ReferenceError
if accessed before they are initialized.