JavaScript Get English count number

We are required to write a JavaScript function that takes in a number and returns an English ordinal number for it (1st, 2nd, 3rd, 4th, etc.).

Example

3 returns 3rd
21 returns 21st
102 returns 102nd

How Ordinal Numbers Work

English ordinal numbers follow these rules:

• Numbers ending in 1: add "st" (1st, 21st, 31st) ? except 11th
• Numbers ending in 2: add "nd" (2nd, 22nd, 32nd) ? except 12th
• Numbers ending in 3: add "rd" (3rd, 23rd, 33rd) ? except 13th
• All others: add "th" (4th, 5th, 6th, 7th, 8th, 9th, 10th, 11th, 12th, 13th)

Implementation

const englishCount = num => {
    if (num % 10 === 1 && num % 100 !== 11) {
        return num + "st";
    }
    if (num % 10 === 2 && num % 100 !== 12) {
        return num + "nd";
    }
    if (num % 10 === 3 && num % 100 !== 13) {
        return num + "rd";
    }
    return num + "th";
};

// Test with various numbers
console.log(englishCount(1));    // 1st
console.log(englishCount(2));    // 2nd
console.log(englishCount(3));    // 3rd
console.log(englishCount(11));   // 11th (exception)
console.log(englishCount(21));   // 21st
console.log(englishCount(102));  // 102nd
console.log(englishCount(111));  // 111th (exception)

1st
2nd
3rd
11th
21st
102nd
111th

How It Works

The function checks the last digit using num % 10 and handles the special cases (11th, 12th, 13th) using num % 100:

• num % 10 gets the last digit
• num % 100 gets the last two digits to handle teens (11, 12, 13)
• The teens (11th, 12th, 13th) always use "th" regardless of their last digit

Alternative Implementation

const getOrdinalSuffix = num => {
    const lastTwoDigits = num % 100;
    const lastDigit = num % 10;
    
    // Handle teens (11th, 12th, 13th)
    if (lastTwoDigits >= 11 && lastTwoDigits  num + getOrdinalSuffix(num);

console.log(englishCountV2(1));   // 1st
console.log(englishCountV2(22));  // 22nd
console.log(englishCountV2(13));  // 13th

1st
22nd
13th

Conclusion

Converting numbers to English ordinals requires handling the special cases of 11th, 12th, and 13th, while applying standard "st", "nd", "rd" rules for other numbers ending in 1, 2, or 3.