Pangram in TypeScript

I’ve been doing Exercism’s TypeScript exercises, and wanted to share my pangram-checking utility.

A pangram is a sentence that contains each of the 26 English letters at least once. Here’s my TypeScript class to determine if a sentence is a pangram.

class Pangram {
  input: string;

  constructor(input: string) {
    this.input = input.toLowerCase();
  }

  isPangram(): boolean {
    const letters = this.input.replace(/[^a-z]/g, '');
    return new Set(letters).size === 26;
  }
}

export default Pangram;

isPangram/0 does the work: replacing all characters not a-z with empty strings (the sentence is already lowercase), breaking the string apart via new Set, and comparing the size to 26. 26 is a borderline magical number, but it’s such a famous one in the English language that I think I get away with it.

• Typescript