Workshop › Text detective › Step 7 of 13

Count each word

What we are doing

Which words repeat? A Map keeps a count for each word: we go through the words and add one to that word's count.

```js
const counts = new Map()
for (const word of words) {
  const key = word.toLowerCase()
  counts.set(key, (counts.get(key) ?? 0) + 1)
}

+ '\nDifferent words: ' + counts.size
```

What it means

• new Map() is an empty word → count table.
• The for loop runs once per word. toLowerCase() makes The and the the same key.
• counts.get(key) ?? 0 is the count so far (0 if the word is new); set stores it plus one.
• counts.size is how many different words there are.

Your turn

1. Under the words line write the counts map and the for loop.
2. Add + '\nDifferent words: ' + counts.size at the end of the report line.

Skills: Loops, Arrays and objects

← An empty box has no words Drop the punctuation →

All steps

1. Read the text
2. Count the characters
3. Update as you type
4. Split into words
5. The extra-space trap
6. An empty box has no words
7. Count each word
8. Drop the punctuation
9. The most common word
10. Shift a letter
11. Encode a whole text
12. The secret line
13. Build it yourself: crack the code