Output using console.log in Javascript - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to print "Hello, world!" to the console.

Javascript

console.[1]("Hello, world!");

Drag options to blanks, or click blank then click option'

Alog

Bwrite

Cprint

Dshow

Attempts:

3 left

💡 Hint

Common Mistakes

Using console.print instead of console.log

Using console.write which is not a valid method

Trying to use console.show which does not exist

The correct method to output text to the console in JavaScript is console.log().

2fill in blank

medium

Complete the code to print the value of variable x to the console.

Javascript

let x = 10;
console.[1](x);

Drag options to blanks, or click blank then click option'

Aprint

Bshow

Cwrite

Dlog

Attempts:

3 left

💡 Hint

Common Mistakes

Using console.print(x)

Using console.write(x)

Using console.show(x)

console.log(x) prints the value of x to the console.

3fill in blank

hard

Fix the error in the code to correctly print "Sum is 15".

Javascript

let a = 7;
let b = 8;
console.[1]("Sum is " + (a + b));

Drag options to blanks, or click blank then click option'

Awrite

Bprint

Clog

Dshow

Attempts:

3 left

💡 Hint

Common Mistakes

Using console.print instead of console.log

Using console.write or console.show which are invalid

console.log is the correct method. The code concatenates strings and numbers correctly.

4fill in blank

hard

Fill both blanks to print the numbers 1 to 5 using a loop.

Javascript

for(let i = 1; i [1] 5; i[2]) {
  console.log(i);
}

Drag options to blanks, or click blank then click option'

A<=

B<

C++

D--

Attempts:

3 left

💡 Hint

Common Mistakes

Using i < 5 which stops at 4

Using i-- which decreases i causing an infinite loop

The loop runs while i is less than or equal to 5, and i increments by 1 each time using i++.

5fill in blank

hard

Fill all three blanks to print only even numbers from 2 to 10.

Javascript

for(let num = [1]; num [2] 10; num[3]) {
  if(num % 2 === 0) {
    console.log(num);
  }
}

Drag options to blanks, or click blank then click option'

A1

B<=

C++

D2

Attempts:

3 left

💡 Hint

Common Mistakes

Starting at 1 which includes odd numbers

Using < instead of <= which excludes 10

Using num-- which causes an infinite loop

Start at 2, loop while num is less than or equal to 10, and increment num by 1 each time.

Practice

1. What does console.log do in JavaScript?

easy

A. It creates a new variable.

B. It stops the program from running.

C. It prints messages or values to the console.

D. It reads input from the user.

Solution

1. Step 1: Understand the purpose of console.log

   console.log is used to show messages or values in the console, helping to see what the program does.

2. Step 2: Compare options with the purpose

   Only It prints messages or values to the console. matches this purpose. Other options describe different actions.

3. Final Answer:

   It prints messages or values to the console. -> Option C

4. Quick Check:

   console.log prints output [OK]

Hint: Remember: console.log shows info in the console [OK]

Common Mistakes:

• Thinking console.log stops the program
• Confusing console.log with input functions
• Assuming console.log creates variables

2. Which of the following is the correct syntax to print "Hello World" using console.log?

easy

A. console.log: 'Hello World'

B. console.print('Hello World')

C. print.console('Hello World')

D. console.log('Hello World')

Solution

1. Step 1: Identify correct console.log syntax

   The correct way to print is console.log('text') with parentheses and quotes around the text.

2. Step 2: Check each option

   console.log('Hello World') uses correct syntax. Options A, B, and C use wrong method names or punctuation.

3. Final Answer:

   console.log('Hello World') -> Option D

4. Quick Check:

   console.log('text') is correct syntax [OK]

Hint: Use console.log() with parentheses and quotes [OK]

Common Mistakes:

• Using console.print instead of console.log
• Missing parentheses
• Using colon instead of parentheses

3. What will be the output of the following code?

let x = 5;
let y = 10;
console.log(x + y);

medium

A. 15

B. 510

C. x + y

D. undefined

Solution

1. Step 1: Understand the variables and operation

   Variables x and y hold numbers 5 and 10. The expression x + y adds these numbers.

2. Step 2: Calculate the sum

   5 + 10 equals 15, so console.log(x + y) prints 15.

3. Final Answer:

   15 -> Option A

4. Quick Check:

   5 + 10 = 15 [OK]

Hint: Add numbers inside console.log to get sum [OK]

Common Mistakes:

• Thinking + concatenates as strings here
• Printing variable names instead of values
• Expecting undefined output

4. Find the error in this code:

console.log('Hello World'

medium

A. Missing closing parenthesis

B. Missing semicolon

C. Wrong quotes used

D. console.log is not a function

Solution

1. Step 1: Check the syntax of console.log

   The function call must have matching opening and closing parentheses.

2. Step 2: Identify the missing part

   The code misses the closing parenthesis after the string, causing a syntax error.

3. Final Answer:

   Missing closing parenthesis -> Option A

4. Quick Check:

   Parentheses must match in function calls [OK]

Hint: Count opening and closing parentheses carefully [OK]

Common Mistakes:

• Ignoring missing parenthesis
• Thinking semicolon is mandatory error
• Confusing quotes with parentheses

5. What will this code print?

let a = 3;
let b = '4';
console.log(a + b);

hard

A. 7

B. 34

C. undefined

D. TypeError

Solution

1. Step 1: Understand the types of variables

   Variable a is a number 3, b is a string '4'.

2. Step 2: Apply + operator with mixed types

   When adding number + string, JavaScript converts number to string and concatenates, so 3 + '4' becomes '34'.

3. Final Answer:

   34 -> Option B

4. Quick Check:

   Number + string concatenates as string [OK]

Hint: Number + string joins as text, not sums [OK]

Common Mistakes:

• Expecting numeric sum
• Thinking it causes error
• Ignoring type conversion rules