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JavaScript Functions and Scope Quiz

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Question 1/15

How will attaching a method `foo` to the object `myObject` affect its behavior, given the following execution?

let myObject = {
  name: 'Sample Object',
  foo: function() {
    return this.name + ' - foo';
  }
};
console.log(myObject.foo());

Select your answer

It logs 'Sample Object - foo'.

It logs 'foo'.

It throws an error.

It logs 'undefined - foo'.

Question 2/15

What does the following function return when called with argument 5?

function increment(x) {
  return ++x;
}

Select your answer

Question 3/15

What will be the output of the following code snippet?

var x = 1;
function outer() {
  var x = 2;
  function inner() {
    var x = 3;
    console.log(x);
  }
  inner();
}
outer();

Select your answer

undefined

Question 4/15

What is the effect of `const` on the variable `num` in this snippet?

const num = 7;
num = 10;

Select your answer

It logs 7 followed by 10.

It causes a TypeError because const variables cannot be reassigned.

It logs 10 without error because of reassignment.

It does nothing and logs 7.

Question 5/15

Consider the below code. What will be logged to the console?

let y = 10;
function modifyVariable() {
  y += 5;
  console.log(y);
}
modifyVariable();

Select your answer

undefined

Question 6/15

Which of the following code snippets correctly declares an IIFE?

// Choose the correct format

Select your answer

()function() {};

(function() {})();

function() {}();

function() {}

Question 7/15

How will the use of `let` affect the availability of variable `z` in the following code?

{
  let z = 10;
  console.log(z);
}
console.log(typeof z);

Select your answer

It logs 10 inside the block but undefined outside.

It throws a SyntaxError.

It logs undefined both inside and outside the block.

It logs 10 both inside and outside the block.

Question 8/15

For this code, what is returned by `compute()`?

function compute() {
  let a = 3;
  let b = 4;
  return a + b;
}

Select your answer

undefined

Question 9/15

Consider the following snippet. What will `calculate(2, 3)` return?

function calculate(a, b = 1) {
  return a * b;
}

Select your answer

Question 10/15

In this code, what will be in the variable `power` after calling `getPower`?

function getPower(base, exponent = 2) {
  return Math.pow(base, exponent);
}
let power = getPower(5);

Select your answer

Question 11/15

In this function declaration, which variable(s) are accessible inside `innerFunction`?

function outerFunction() {
  var outerVar = 'outer';
  function innerFunction() {
    console.log(outerVar);
  }
}

Select your answer

Only innerscope variables.

None, since outerVar is outside the innerFunction.

outerVar and innerVar, assuming innerVar existed.

Only outerVar, as it's enclosed in the parent function scope.

Question 12/15

What value will the variable `result` hold?

function multiplier(a, b = 2) {
  return a * b;
}
let result = multiplier(4);

Select your answer

Question 13/15

What will be the output of this immediately invoked function expression?

(function() {
  var a = b = 5;
})();
console.log(typeof a);
console.log(typeof b);

Select your answer

number and undefined

undefined and number

undefined and undefined

Question 14/15

What is the impact of calling `comparison(5, '5')` in this code?

function comparison(x, y) {
  return x == y;
}

Select your answer

The function returns false as it compares different types.

It throws a TypeError.

It always returns undefined.

The function returns true due to type coercion.

Question 15/15

What is the effect of calling `sum(4, 5, 6)` in the given code?

function sum(x, y, ...rest) {
  return x + y;
}

Select your answer

ReferenceError

Your Results

You did not answer any questions correctly.

Your Answers

Question 1/15

😊 Your answer was correct 🙁 Your answer was incorrect

How will attaching a method `foo` to the object `myObject` affect its behavior, given the following execution?

let myObject = {
  name: 'Sample Object',
  foo: function() {
    return this.name + ' - foo';
  }
};
console.log(myObject.foo());

Available answers

It logs 'Sample Object - foo'.

It logs 'foo'.

It throws an error.

It logs 'undefined - foo'.

The method `foo` returns the object's `name` property concatenated with ' - foo'. Since `this` refers to `myObject`, it logs 'Sample Object - foo'.

Question 2/15

😊 Your answer was correct 🙁 Your answer was incorrect

What does the following function return when called with argument 5?

function increment(x) {
  return ++x;
}

Available answers

The function uses the prefix increment operator, which increases the value of x by one before the value is returned. So, calling increment(5) returns 6.

Question 3/15

😊 Your answer was correct 🙁 Your answer was incorrect

What will be the output of the following code snippet?

var x = 1;
function outer() {
  var x = 2;
  function inner() {
    var x = 3;
    console.log(x);
  }
  inner();
}
outer();

Available answers

undefined

The code defines three variables called x in different scopes. The innermost x (with value 3) is in the inner function's scope, and that's the one that is logged by console.log.

Question 4/15

😊 Your answer was correct 🙁 Your answer was incorrect

What is the effect of `const` on the variable `num` in this snippet?

const num = 7;
num = 10;

Available answers

It logs 7 followed by 10.

It causes a TypeError because const variables cannot be reassigned.

It logs 10 without error because of reassignment.

It does nothing and logs 7.

Since `num` is declared with `const`, it cannot be reassigned without resulting in a TypeError.

Question 5/15

😊 Your answer was correct 🙁 Your answer was incorrect

Consider the below code. What will be logged to the console?

let y = 10;
function modifyVariable() {
  y += 5;
  console.log(y);
}
modifyVariable();

Available answers

undefined

Since y is declared outside the function with a value of 10, and the function modifyVariable adds 5 to y, the logged value will be 15.

Question 6/15

😊 Your answer was correct 🙁 Your answer was incorrect

Which of the following code snippets correctly declares an IIFE?

// Choose the correct format

Available answers

()function() {};

(function() {})();

function() {}();

function() {}

An IIFE (Immediately Invoked Function Expression) can be declared with (function() {})();, enclosing the function in parentheses followed by immediate invocation.

Question 7/15

😊 Your answer was correct 🙁 Your answer was incorrect

How will the use of `let` affect the availability of variable `z` in the following code?

{
  let z = 10;
  console.log(z);
}
console.log(typeof z);

Available answers

It logs 10 inside the block but undefined outside.

It throws a SyntaxError.

It logs undefined both inside and outside the block.

It logs 10 both inside and outside the block.

The block scope defined by the braces makes `z` accessible only within the block due to `let`. Thus, it logs 10 within and undefined outside.

Question 8/15

😊 Your answer was correct 🙁 Your answer was incorrect

For this code, what is returned by `compute()`?

function compute() {
  let a = 3;
  let b = 4;
  return a + b;
}

Available answers

undefined

`compute` evaluates the sum of `a` and `b`, which is 3 + 4, resulting in 7.

Question 9/15

😊 Your answer was correct 🙁 Your answer was incorrect

Consider the following snippet. What will `calculate(2, 3)` return?

function calculate(a, b = 1) {
  return a * b;
}

Available answers

The function `calculate` multiplies its two arguments. The second argument `b` defaults to 1 if not provided. Calling calculate(2, 3) multiplies 2 by 3, which results in 6.

Question 10/15

😊 Your answer was correct 🙁 Your answer was incorrect

In this code, what will be in the variable `power` after calling `getPower`?

function getPower(base, exponent = 2) {
  return Math.pow(base, exponent);
}
let power = getPower(5);

Available answers

The function `getPower` defaults `exponent` to 2 if not provided, so `Math.pow(5, 2)` computes 5^2, which equals 25.

Question 11/15

😊 Your answer was correct 🙁 Your answer was incorrect

In this function declaration, which variable(s) are accessible inside `innerFunction`?

function outerFunction() {
  var outerVar = 'outer';
  function innerFunction() {
    console.log(outerVar);
  }
}

Available answers

Only innerscope variables.

None, since outerVar is outside the innerFunction.

outerVar and innerVar, assuming innerVar existed.

Only outerVar, as it's enclosed in the parent function scope.

`innerFunction` has access to variables within its parent's scope due to closures, allowing access to `outerVar`.

Question 12/15

😊 Your answer was correct 🙁 Your answer was incorrect

What value will the variable `result` hold?

function multiplier(a, b = 2) {
  return a * b;
}
let result = multiplier(4);

Available answers

The function `multiplier` defaults `b` to 2 if not provided. The call `multiplier(4)` is thus 4 * 2, resulting in 8.

Question 13/15

😊 Your answer was correct 🙁 Your answer was incorrect

What will be the output of this immediately invoked function expression?

(function() {
  var a = b = 5;
})();
console.log(typeof a);
console.log(typeof b);

Available answers

number and undefined

undefined and number

undefined and undefined

In the IIFE, `b` is assigned to 5 in the global scope because it's not declared with var, let, or const. `a` is only defined within the function's scope, so it is undefined outside. The console logs 'undefined' and 'number'.

Question 14/15

😊 Your answer was correct 🙁 Your answer was incorrect

What is the impact of calling `comparison(5, '5')` in this code?

function comparison(x, y) {
  return x == y;
}

Available answers

The function returns false as it compares different types.

It throws a TypeError.

It always returns undefined.

The function returns true due to type coercion.

The loose equality `==` allows type coercion, so `comparison(5, '5')` evaluates to true.

Question 15/15

😊 Your answer was correct 🙁 Your answer was incorrect

What is the effect of calling `sum(4, 5, 6)` in the given code?

function sum(x, y, ...rest) {
  return x + y;
}

Available answers

ReferenceError

The `sum` function calculates the sum of only the first two arguments, ignoring the rest, so `sum(4, 5, 6)` results in 4 + 5, outputting 9.