Determining a pangram string in JavaScript

A pangram is a string that contains every letter of the English alphabet at least once. Examples include "The quick brown fox jumps over the lazy dog" and "Pack my box with five dozen liquor jugs".

We need to write a JavaScript function that determines whether a given string is a pangram. For this problem, we'll focus on the 26 letters of the English alphabet, ignoring case sensitivity.

How It Works

The algorithm creates an array of all 26 letters, then iterates through the input string. For each letter found in the string, it removes that letter from the alphabet array. If all letters are found, the array becomes empty, indicating a pangram.

Example

const str = 'We promptly judged antique ivory buckles for the next prize';

const isPangram = (str = '') => {
    str = str.toLowerCase();
    const { length } = str;
    const alphabets = 'abcdefghijklmnopqrstuvwxyz';
    const alphaArr = alphabets.split('');
    
    for(let i = 0; i 

true
false
true


Using Set for Better Performance

A more efficient approach uses a Set to track found letters:

const isPangramSet = (str = '') => {
    const letters = new Set();
    str = str.toLowerCase();
    
    for(let char of str) {
        if(char >= 'a' && char 

true
false


Comparison

Key Points

• Convert input to lowercase for case-insensitive checking
• A pangram must contain all 26 letters of the alphabet
• The Set approach is more efficient for longer strings
• Both methods ignore non-alphabetic characters

Conclusion

Both approaches effectively detect pangrams, but the Set method offers better performance. Use the array method for learning purposes and the Set approach for production code with large inputs.