← ⚡ JavaScript World

⚡ Sum It All

★★☆☆☆ · worth 100 points

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📖 The mission

Today you unlock

Loops inspect each item

Many levels use a loop: start with a simple value, visit each item, update the answer, then return it at the end.

💡 Hint ladder

A for...of loop can visit every number: for (const n of numbers) { ... }
Start a total at 0 and add each number to it.

🧪 Coach checks

◯ adds 1+2+3
◯ empty array is 0
◯ single number
◯ negative numbers

Live coach

Getting ready

☆☆☆

💬 A loop visits every item in an array. Watch the total grow.

function countItems(items) {
  let count = 0;
  for (const item of items) {
    count = count + 1;
  }
  return count;
}

console.log(countItems(["a", "b", "c"]));  // 3

📟 It printed:

📟 Output