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All questions of Scope and Hoisting for Software Development Exam
What is the output of the following code snippet?
var x = 5;function foo() {
console.log(x);
var x = 10;
function bar() {
console.log(x);
}
bar();
}foo();- a)0, 0
- b)undefined, undefined
- c)10, 10
- d)undefined, 10
Correct answer is option 'D'. Can you explain this answer?
What is the output of the following code snippet?
var x = 5;
var x = 5;
function foo() {
console.log(x);
var x = 10;
function bar() {
console.log(x);
}
bar();
}
console.log(x);
var x = 10;
function bar() {
console.log(x);
}
bar();
}
foo();
a)
0, 0
b)
undefined, undefined
c)
10, 10
d)
undefined, 10
|
Qudrat Chauhan answered |
The variable x is declared in the function foo but is not assigned a value before the first console.log statement. Therefore, it outputs undefined. Inside the bar function, it logs the value of x, which is 10.
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What is the output of the following code?
var x = 5;
(function () {
console.log(x);
var x = 10;
})();- a)undefined
- b)ReferenceError
- c)5
- d)10
Correct answer is option 'A'. Can you explain this answer?
What is the output of the following code?
var x = 5;
(function () {
console.log(x);
var x = 10;
})();
var x = 5;
(function () {
console.log(x);
var x = 10;
})();
a)
undefined
b)
ReferenceError
c)
5
d)
10
|
Tech Era answered |
In this code, the variable "x" is declared and assigned a value of 5. Inside the immediately invoked function expression (IIFE), a new variable "x" is declared using var and assigned a value of 10. Since the scope of the IIFE is separate from the outer scope, the console.log inside the IIFE prints "undefined" because the local "x" overshadows the outer "x".
What is the output of the following code snippet?
var x = 5;function foo() {
console.log(x);
}function bar() {
var x = 10;
foo();
}bar();- a)0
- b)undefined
- c)5
- d)ReferenceError
Correct answer is option 'C'. Can you explain this answer?
What is the output of the following code snippet?
var x = 5;
var x = 5;
function foo() {
console.log(x);
}
console.log(x);
}
function bar() {
var x = 10;
foo();
}
var x = 10;
foo();
}
bar();
a)
0
b)
undefined
c)
5
d)
ReferenceError
|
Vikram Singh Baghel answered |
The function foo has access to the global variable x, which is 5. When the foo function is called from the bar function, it logs the value of x, which is 5.
What is the output of the following code snippet?
var x = 5;function foo() {
console.log(this.x);
}var obj = {
x: 10,
foo: foo,
};var bar = obj.foo;
bar();- a)0
- b)undefined
- c)5
- d)10
Correct answer is option 'B'. Can you explain this answer?
What is the output of the following code snippet?
var x = 5;
var x = 5;
function foo() {
console.log(this.x);
}
console.log(this.x);
}
var obj = {
x: 10,
foo: foo,
};
x: 10,
foo: foo,
};
var bar = obj.foo;
bar();
bar();
a)
0
b)
undefined
c)
5
d)
10
|
|
Vikram Singh Baghel answered |
The function bar is assigned to the variable bar, and when it is called, the "this" keyword refers to the global object (window in a browser environment). Since the global object does not have a property x, it outputs undefined.
What is the output of the following code snippet?
var x = 5;function foo() {
console.log(x);
var x = 10;
}foo();- a)0
- b)undefined
- c)5
- d)ReferenceError
Correct answer is option 'B'. Can you explain this answer?
What is the output of the following code snippet?
var x = 5;
var x = 5;
function foo() {
console.log(x);
var x = 10;
}
console.log(x);
var x = 10;
}
foo();
a)
0
b)
undefined
c)
5
d)
ReferenceError
|
|
Qudrat Chauhan answered |
The variable x is declared inside the function foo using "var," which creates a local scope. At the time of the first console.log statement, the variable x exists but has not been assigned a value yet, resulting in undefined.
What will be the value of "result" after executing the following code?
var x = 2;
(function () {
x = 5;
})();
var result = x * 3;- a)2
- b)5
- c)3
- d)15
Correct answer is option 'A'. Can you explain this answer?
What will be the value of "result" after executing the following code?
var x = 2;
(function () {
x = 5;
})();
var result = x * 3;
var x = 2;
(function () {
x = 5;
})();
var result = x * 3;
a)
2
b)
5
c)
3
d)
15
|
|
Tech Era answered |
The variable "x" is initially assigned a value of 2. Inside the IIFE, the value of "x" is changed to 5. After the IIFE, the value of "x" is 5, and the multiplication "x * 3" gives the result of 15.
What will be the output of the following code?- a)5, 10
- b)10, 5
- c)5, 5
- d)ReferenceError
Correct answer is option 'B'. Can you explain this answer?
What will be the output of the following code?
a)
5, 10
b)
10, 5
c)
5, 5
d)
ReferenceError
|
|
Tech Era answered |
Inside the IIFE, a new variable "x" is declared and assigned a value of 10. This "x" is local to the IIFE and does not affect the outer "x" with a value of 5. Therefore, the first console.log outputs 10, and the second console.log outputs 5.
What is the global scope in JavaScript?- a)The scope inside a function where local variables are declared
- b)The scope that is accessible from anywhere in the program
- c)The scope that contains only global variables
- d)The scope used for temporary variables in loops
Correct answer is option 'B'. Can you explain this answer?
What is the global scope in JavaScript?
a)
The scope inside a function where local variables are declared
b)
The scope that is accessible from anywhere in the program
c)
The scope that contains only global variables
d)
The scope used for temporary variables in loops
|
Yogesh Dwivedi answered |
The global scope in JavaScript refers to the scope that is accessible from anywhere in the program, including inside functions.
What is the output of the following code snippet?
console.log(x);var x = 5;- a)0
- b)undefined
- c)5
- d)ReferenceError
Correct answer is option 'B'. Can you explain this answer?
What is the output of the following code snippet?
console.log(x);
console.log(x);
var x = 5;
a)
0
b)
undefined
c)
5
d)
ReferenceError
|
|
Qudrat Chauhan answered |
Variable declarations with "var" are hoisted to the top, but the assignment is not hoisted. Thus, at the time of the console.log statement, the variable x exists but has not been assigned a value, resulting in undefined.
What is the output of the following code snippet?
var x = 10;function foo() {
var x = 20;
function bar() {
var x = 30;
console.log(x);
}
bar();
}foo();- a)10
- b)20
- c)30
- d)undefined
Correct answer is option 'C'. Can you explain this answer?
What is the output of the following code snippet?
var x = 10;
var x = 10;
function foo() {
var x = 20;
function bar() {
var x = 30;
console.log(x);
}
bar();
}
var x = 20;
function bar() {
var x = 30;
console.log(x);
}
bar();
}
foo();
a)
10
b)
20
c)
30
d)
undefined
|
Simar Sharma answered |
The variable x is declared in different scopes: 10 in the bar function and 30 in the innermost block. The console.log statement inside the bar function outputs the value of x within its scope, which is 30.
What is the value of "result" after executing the following code?
function multiplyByTwo(num) {
var result = num * 2;
return function () {
console.log(result);
};
}
var multiplyByTwoFn = multiplyByTwo(5);
multiplyByTwoFn();- a)5
- b)10
- c)undefined
- d)ReferenceError
Correct answer is option 'B'. Can you explain this answer?
What is the value of "result" after executing the following code?
function multiplyByTwo(num) {
var result = num * 2;
return function () {
console.log(result);
};
}
var multiplyByTwoFn = multiplyByTwo(5);
multiplyByTwoFn();
function multiplyByTwo(num) {
var result = num * 2;
return function () {
console.log(result);
};
}
var multiplyByTwoFn = multiplyByTwo(5);
multiplyByTwoFn();
a)
5
b)
10
c)
undefined
d)
ReferenceError
|
|
Tech Era answered |
The "multiplyByTwo" function takes a number and returns an anonymous function. The anonymous function logs the value of the "result" variable, which is the input number multiplied by 2. When "multiplyByTwoFn" is invoked, it calls the returned anonymous function and outputs the value of "result", which is 10.
What is the difference between var and let in terms of hoisting?- a)Variables declared with var are hoisted, but let variables are not
- b)Variables declared with let are hoisted, but var variables are not
- c)Both var and let variables are hoisted in the same way
- d)Variables declared with var and let are not hoisted
Correct answer is option 'A'. Can you explain this answer?
What is the difference between var and let in terms of hoisting?
a)
Variables declared with var are hoisted, but let variables are not
b)
Variables declared with let are hoisted, but var variables are not
c)
Both var and let variables are hoisted in the same way
d)
Variables declared with var and let are not hoisted
|
Tanuja Mishra answered |
Variables declared with var are hoisted to the top of their scope, allowing them to be accessed before they are declared. On the other hand, let variables are not hoisted and cannot be accessed before their declaration.
What is the output of the following code?
function example() {
console.log(x);
var x = 10;
}
example();- a)undefined
- b)ReferenceError
- c)10
- d)NaN
Correct answer is option 'A'. Can you explain this answer?
What is the output of the following code?
function example() {
console.log(x);
var x = 10;
}
example();
function example() {
console.log(x);
var x = 10;
}
example();
a)
undefined
b)
ReferenceError
c)
10
d)
NaN
|
CodeNation answered |
Similar to the previous question, the variable "x" is hoisted to the top of the function scope. However, its value is not assigned until the line "var x = 10;" is reached, resulting in the output "undefined".
What is the output of the following code?
console.log(a);
let a = 7;- a)undefined
- b)ReferenceError
- c)7
- d)NaN
Correct answer is option 'B'. Can you explain this answer?
What is the output of the following code?
console.log(a);
let a = 7;
console.log(a);
let a = 7;
a)
undefined
b)
ReferenceError
c)
7
d)
NaN
|
|
CodeNation answered |
In this code, the variable "a" is declared using let, which is block-scoped. Since let variables are not hoisted, trying to access "a" before its declaration results in a ReferenceError.
What is the output of the following code?
function example() {
console.log(a);
let a = 3;
}
example();- a)undefined
- b)ReferenceError
- c)3
- d)NaN
Correct answer is option 'B'. Can you explain this answer?
What is the output of the following code?
function example() {
console.log(a);
let a = 3;
}
example();
function example() {
console.log(a);
let a = 3;
}
example();
a)
undefined
b)
ReferenceError
c)
3
d)
NaN
|
|
Simar Sharma answered |
This question is similar to the previous one. The variable "a" is declared using let, which is block-scoped. Accessing "a" before its declaration results in a ReferenceError.
What is the output of the following code snippet?
var x = 5;function foo() {
console.log(x);
}foo();- a)0
- b)undefined
- c)5
- d)ReferenceError
Correct answer is option 'C'. Can you explain this answer?
What is the output of the following code snippet?
var x = 5;
var x = 5;
function foo() {
console.log(x);
}
console.log(x);
}
foo();
a)
0
b)
undefined
c)
5
d)
ReferenceError
|
|
Qudrat Chauhan answered |
The variable x is declared in the global scope, and the function foo has access to it. When the foo function is called, it logs the value of x, which is 5.
What is the output of the following code snippet?
function foo() {
console.log(x);
}foo();var x = 10;- a)0
- b)undefined
- c)10
- d)ReferenceError
Correct answer is option 'B'. Can you explain this answer?
What is the output of the following code snippet?
function foo() {
console.log(x);
}
function foo() {
console.log(x);
}
foo();
var x = 10;
a)
0
b)
undefined
c)
10
d)
ReferenceError
|
|
Qudrat Chauhan answered |
The variable x is declared after the function call, so at the time of the console.log statement, it exists but has not been assigned a value yet. Hence, it outputs undefined.
What is the scope of a variable in JavaScript?- a)The scope of a variable defines its visibility and lifetime.
- b)The scope of a variable determines its data type.
- c)The scope of a variable determines its initial value.
- d)The scope of a variable determines its function name.
Correct answer is option 'A'. Can you explain this answer?
What is the scope of a variable in JavaScript?
a)
The scope of a variable defines its visibility and lifetime.
b)
The scope of a variable determines its data type.
c)
The scope of a variable determines its initial value.
d)
The scope of a variable determines its function name.
|
Code Nation answered |
The scope of a variable in JavaScript defines the region or part of the program where the variable is accessible or visible. It also determines the lifetime or duration of the variable, including when it is created and when it is destroyed.
What happens if a variable is declared without the "var," "let," or "const" keyword?- a)An error occurs because JavaScript requires variable declarations.
- b)The variable is automatically assigned a global scope.
- c)The variable is only accessible within the current block scope.
- d)The variable is automatically assigned a local scope.
Correct answer is option 'B'. Can you explain this answer?
What happens if a variable is declared without the "var," "let," or "const" keyword?
a)
An error occurs because JavaScript requires variable declarations.
b)
The variable is automatically assigned a global scope.
c)
The variable is only accessible within the current block scope.
d)
The variable is automatically assigned a local scope.
|
Neeraj Singh Kushwah answered |
In JavaScript, if a variable is declared without using the 'var', 'let', or 'const' keyword, it is automatically assigned a global scope. This behavior is known as implicit global variable declaration.
When a variable is declared without any explicit declaration keyword ('var', 'let', or 'const'), it becomes a global variable. This means that the variable is accessible from anywhere within the program, including inside functions, blocks, and other scopes.
What is the output of the following code snippet?
function foo() {
console.log(x);
}foo();let x = 10;- a)0
- b)undefined
- c)10
- d)ReferenceError
Correct answer is option 'D'. Can you explain this answer?
What is the output of the following code snippet?
function foo() {
console.log(x);
}
function foo() {
console.log(x);
}
foo();
let x = 10;
a)
0
b)
undefined
c)
10
d)
ReferenceError
|
|
Qudrat Chauhan answered |
The variable x is declared using "let" which has block scope. When the console.log statement is executed before the variable x is declared, a ReferenceError occurs.
What is the output of the following code?
function outer() {
var x = 1;
function inner() {
console.log(x);
}
x = 2;
return inner;
}
var fn = outer();
fn();- a)1
- b)2
- c)undefined
- d)ReferenceError
Correct answer is option 'B'. Can you explain this answer?
What is the output of the following code?
function outer() {
var x = 1;
function inner() {
console.log(x);
}
x = 2;
return inner;
}
var fn = outer();
fn();
function outer() {
var x = 1;
function inner() {
console.log(x);
}
x = 2;
return inner;
}
var fn = outer();
fn();
a)
1
b)
2
c)
undefined
d)
ReferenceError
|
|
Tech Era answered |
The outer function "outer" has a variable "x" assigned a value of 1. Inside the function, an inner function "inner" is defined, which accesses and logs the value of "x". Before returning the inner function, the value of "x" is changed to 2. When the returned "fn" function is invoked, it outputs the value of "x", which is 2.
Which keyword is used to declare a block-scoped variable in JavaScript?- a)let
- b)var
- c)const
- d)function
Correct answer is option 'A'. Can you explain this answer?
Which keyword is used to declare a block-scoped variable in JavaScript?
a)
let
b)
var
c)
const
d)
function
|
|
Tanuja Mishra answered |
The "let" keyword is used to declare block-scoped variables in JavaScript. Block scope means the variable is accessible only within the block it is defined in.
What is the value of "sum" after executing the following code?
var sum = 0;
for (var i = 0; i < 5; i++) {
sum += i;
}
console.log(i);- a)4
- b)5
- c)10
- d)ReferenceError
Correct answer is option 'B'. Can you explain this answer?
What is the value of "sum" after executing the following code?
var sum = 0;
for (var i = 0; i < 5; i++) {
sum += i;
}
console.log(i);
var sum = 0;
for (var i = 0; i < 5; i++) {
sum += i;
}
console.log(i);
a)
4
b)
5
c)
10
d)
ReferenceError
|
|
Tech Era answered |
The variable "sum" is initialized as 0. The "for" loop iterates from 0 to 4, adding each value of "i" to "sum". After the loop, the value of "i" is accessible outside the loop and is equal to 5.
What is hoisting in JavaScript?- a)The process of moving variable declarations to the top of their scope
- b)The process of assigning a value to a variable
- c)The process of removing unused variables from memory
- d)The process of dynamically changing the scope of a variable
Correct answer is option 'A'. Can you explain this answer?
What is hoisting in JavaScript?
a)
The process of moving variable declarations to the top of their scope
b)
The process of assigning a value to a variable
c)
The process of removing unused variables from memory
d)
The process of dynamically changing the scope of a variable
|
|
Tanuja Mishra answered |
Hoisting is a JavaScript behavior where variable declarations are moved to the top of their scope during the compilation phase, allowing variables to be accessed before they are declared.
What is the scope of a variable in JavaScript?- a)The visibility or accessibility of a variable within a specific part of a program
- b)The time during which a variable exists or holds a value
- c)The process of assigning a value to a variable
- d)The space allocated in memory for storing a variable's value
Correct answer is option 'A'. Can you explain this answer?
What is the scope of a variable in JavaScript?
a)
The visibility or accessibility of a variable within a specific part of a program
b)
The time during which a variable exists or holds a value
c)
The process of assigning a value to a variable
d)
The space allocated in memory for storing a variable's value
|
|
Yogesh Dwivedi answered |
The scope of a variable determines where it is accessible within the program. It defines the region of code where a variable can be referenced.
Which type of scope allows a variable to be accessed from anywhere within the program?- a)Local scope
- b)Global scope
- c)Block scope
- d)Function scope
Correct answer is option 'B'. Can you explain this answer?
Which type of scope allows a variable to be accessed from anywhere within the program?
a)
Local scope
b)
Global scope
c)
Block scope
d)
Function scope
|
|
Code Nation answered |
Global scope in JavaScript allows a variable to be accessed from anywhere within the program. Variables declared outside of any function or block have global scope. They are accessible throughout the entire program, including within functions, blocks, and other scopes.
What is hoisting in JavaScript?- a)Hoisting is a technique to optimize code execution.
- b)Hoisting is the process of moving variable and function declarations to the top of their scope.
- c)Hoisting is a security mechanism to prevent code injection.
- d)Hoisting is the process of converting JavaScript code into machine code.
Correct answer is option 'B'. Can you explain this answer?
What is hoisting in JavaScript?
a)
Hoisting is a technique to optimize code execution.
b)
Hoisting is the process of moving variable and function declarations to the top of their scope.
c)
Hoisting is a security mechanism to prevent code injection.
d)
Hoisting is the process of converting JavaScript code into machine code.
|
|
Code Nation answered |
Hoisting in JavaScript is a behavioral characteristic of the language where variable and function declarations are moved to the top of their containing scope during the compilation phase, before the actual execution of the code.
Hoisting affects both variable and function declarations, but not their assignments or initializations. It means that while the declarations are hoisted, the assignments or initializations remain in their original position.
What is the output of the following code snippet?
var x = 5;function foo() {
console.log(x);
}function bar() {
foo();
var x = 10;
}bar();- a)0
- b)undefined
- c)5
- d)ReferenceError
Correct answer is option 'B'. Can you explain this answer?
What is the output of the following code snippet?
var x = 5;
var x = 5;
function foo() {
console.log(x);
}
console.log(x);
}
function bar() {
foo();
var x = 10;
}
foo();
var x = 10;
}
bar();
a)
0
b)
undefined
c)
5
d)
ReferenceError
|
|
Vikram Singh Baghel answered |
The function foo is called before the variable x is assigned a value in the bar function. Therefore, at the time of the console.log statement in the foo function, x exists but has not been assigned a value yet, resulting in undefined.
What is the output of the following code?
console.log(x);
var x = 5;- a)undefined
- b)ReferenceError
- c)5
- d)NaN
Correct answer is option 'A'. Can you explain this answer?
What is the output of the following code?
console.log(x);
var x = 5;
console.log(x);
var x = 5;
a)
undefined
b)
ReferenceError
c)
5
d)
NaN
|
Codebreakers answered |
In JavaScript, variable declarations (not assignments) are hoisted to the top of their scope. So, the variable "x" is hoisted, but its value is not assigned at that point, resulting in the output "undefined".
What is the difference between "var" and "let" when it comes to variable hoisting?- a)"var" variables are hoisted to the top of the function, while "let" variables are hoisted to the top of the block.
- b)"var" variables are hoisted to the top of the block, while "let" variables are hoisted to the top of the function.
- c)Both "var" and "let" variables are hoisted to the top of their respective scopes.
- d)"var" variables are not hoisted, while "let" variables are hoisted to the top of the block.
Correct answer is option 'A'. Can you explain this answer?
What is the difference between "var" and "let" when it comes to variable hoisting?
a)
"var" variables are hoisted to the top of the function, while "let" variables are hoisted to the top of the block.
b)
"var" variables are hoisted to the top of the block, while "let" variables are hoisted to the top of the function.
c)
Both "var" and "let" variables are hoisted to the top of their respective scopes.
d)
"var" variables are not hoisted, while "let" variables are hoisted to the top of the block.
|
|
Qudrat Chauhan answered |
The behavior of variable hoisting differs between "var" and "let" declarations in JavaScript.
- Hoisting with "var": When a variable is declared using the "var" keyword, its declaration is hoisted to the top of the nearest function scope. This means that the variable declaration is moved to the top of its containing function, regardless of where it appears in the code. However, the assignment or initialization of the variable remains in its original position.Example:
function example() {
console.log(x); // Output: undefined
var x = 5;
} - In the above code, even though the variable x is accessed before its declaration, the declaration is hoisted to the top of the function scope. This is why the output of console.log(x) is undefined instead of throwing a ReferenceError. Hoisting with "let": When a variable is declared using the "let" keyword, its declaration is hoisted to the top of the nearest block scope (inside curly braces {}). This means that the variable declaration is moved to the top of the block in which it appears, regardless of its position within the block. Similar to "var" variables, the assignment or initialization of the variable remains in its original position.
Example:
function example() {
console.log(x); // Throws ReferenceError: Cannot access 'x' before initialization
let x = 5;
}
In the above code, accessing the variable x before its declaration throws a ReferenceError. Unlike "var" variables, "let" variables are not accessible before their declaration within the block scope.
To summarize, "var" variables are hoisted to the top of the function scope, while "let" variables are hoisted to the top of the block scope. Understanding these differences is crucial for managing variable visibility and preventing unintended behavior in JavaScript code.
Chapter doubts & questions for Scope and Hoisting - JavaScript for Web Development 2024 is part of Software Development exam preparation. The chapters have been prepared according to the Software Development exam syllabus. The Chapter doubts & questions, notes, tests & MCQs are made for Software Development 2024 Exam. Find important definitions, questions, notes, meanings, examples, exercises, MCQs and online tests here.
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