JavaScript: Iteration

Question 1

Why is a “for loop” used?

Answer 1

We use a for loop to execute code more than once.

Question 2

What are the three parts of a “for loop?”
What is the syntax?

Answer 2

1. declare counter (index)
2. declare expression saying how long the loop will run (end condition)
3. How to increment or decrement your counter variable

for (let i = 0; i <= 1; i++) {
console.log(‘This is the current value of i: ${i}.`);
}

Note: i++ is shorthand for i + 1

Question 3

How would you use a “for loop” to create a numbered list of all data in the array?
What is the syntax?

Answer 3

const zooAnimals = [“Bears”, “Giraffes”, “Penguins”, “Meerkats”];
…

for (let i = 0; i < zooAnimals.length; i++) {
console.log( ‘${i + 1}) ${zooAnimals[i]}`);
}

Question 4

How would you use a “for loop” to create a list of all data in the array (without index numbers)?
What is the syntax?

Answer 4

const zooAnimals = [“Bears”, “Giraffes”, “Penguins”, “Meerkats”];
…

for (const animal of zooAnimals) {
console.log(animal);
}