Loop execution flow in Javascript - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is the main purpose of a loop in programming?

A loop repeats a block of code multiple times until a condition is met or no longer true.

beginner

What are the three main parts of a for loop in JavaScript?

Initialization (start value), condition (when to stop), and update (how to change the value each time).

intermediate

What happens if the loop condition is always true?

The loop runs forever, causing an infinite loop that can freeze or crash the program.

intermediate

How does a while loop differ from a do...while loop?

A while loop checks the condition before running the code, but do...while runs the code once before checking the condition.

beginner

What is the role of the break statement inside a loop?

It immediately stops the loop and exits it, even if the loop condition is still true.

Which part of a for loop runs only once at the start?

A Body

B Condition

C Initialization

D Update

Initialization sets the starting point and runs once before the loop begins.

What will happen if the condition in a while loop is false at the start?

A The loop will run infinitely

B The loop body will not run at all

C The loop body will run once

D The loop will run twice

A while loop checks the condition first, so if false, it skips the loop body.

What does the continue statement do inside a loop?

A Skips the rest of the current loop iteration and moves to the next

B Stops the loop completely

C Restarts the loop from the beginning

D Exits the program

continue skips the remaining code in the current loop cycle and jumps to the next iteration.

In a do...while loop, when is the condition checked?

A Multiple times before each iteration

B Before the loop runs

C Never

D After the loop runs once

The do...while loop runs the code once, then checks the condition to decide if it repeats.

What is the output of this code?<br>

for(let i = 0; i < 3; i++) {<br>  if(i === 1) break;<br>  console.log(i);<br>}

A 0

B 0 1 2

C 1 2

D No output

The loop stops when i equals 1, so only 0 is printed.

Explain how a for loop executes step-by-step.

Think about the order of the three parts and when the code inside runs.

Describe the difference between while and do...while loops.

Focus on when the condition is checked in each loop.