Iteration (Loops)

What is iteration?

Iteration means repeating code multiple times using loops. Instead of writing the same code over and over, you can use a loop to run it as many times as needed.

Benefits of iteration?

• Repeat actions without duplicating code
• Process all items in an array or list
• Handle repetitive tasks automatically
• Update game objects every frame
• Scale to handle any number of items

// for loop
for (let i = 0; i < 5; i++) {
    console.log("Loop iteration: " + i);
}

// while loop
let count = 0;
while (count < 3) {
    console.log("Count: " + count);
    count++;
}

// forEach
const gameObjects = ['player', 'guard', 'npc'];
gameObjects.forEach(function(object) {
    console.log("Updating: " + object);
});

// for...of loop
for (const object of gameObjects) {
    console.log("Object: " + object);
}

What does this code do?

• Uses for loop to run code exactly 5 times
• Uses while loop to repeat while condition is true
• Uses forEach() to run function for each array item
• Uses for...of loop for cleaner array iteration
• Shows different loop styles for different situations

// Practical example: update all game objects
const objects = [
    { name: 'player', x: 100 },
    { name: 'guard', x: 200 },
    { name: 'npc', x: 300 }
];

for (let obj of objects) {
    obj.x += 5; // Move each object right
    console.log(obj.name + " moved to " + obj.x);
}

What does this code do?

• Updates each object in the array one by one
• Uses for...of to iterate through the array
• Modifies each object’s position by adding 5
• Shows how iteration is essential for game updates
• Processes all game objects in a single loop

Try It Yourself

%%js // CODE_RUNNER: iteration for (let i = 0; i < 3; i++) { console.log(“Iteration: “ + i); } const items = [‘player’, ‘enemy’]; items.forEach(item => console.log(item));