Step by Step solution about How to resolve the algorithm Pangram checker step by step in the JavaScript programming language

The provided code snippet contains two implementations of a function that checks if a given string is a pangram. A pangram is a sentence that contains every letter of the alphabet at least once.

Implementation 1:

• The isPangram function takes a string s as input.
• It initializes a string letters containing all the lowercase letters of the alphabet sorted by frequency (ascending).
• It converts the input string s to lowercase and removes all non-alphabetic characters.
• It loops through each letter in the letters string and checks if it exists in the processed input string s.
• If any letter is not found in s, the function returns false.
• If all letters are found in s, the function returns true.

Implementation 2:

• This implementation uses more modern JavaScript features with arrow functions and template literals.
• The isPangram function takes a string s as input.
• It uses the toLowerCase() method to convert the input string to lowercase.
• It uses the split() method to create an array of all characters in the alphabet.
• It uses the filter() method to remove characters from the array that are not present in the lowercase input string.
• It returns 0 if the length of the filtered array is 0, indicating that all characters are present. Otherwise, it returns a non-zero value, indicating that not all characters are present.

Usage:

Both implementations are used to check if two example strings ("is this a pangram" and "The quick brown fox jumps over the lazy dog") are pangrams. The expected output is:

• false for the first example (not a pangram)
• true for the second example (a pangram)

function isPangram(s) {
    var letters = "zqxjkvbpygfwmucldrhsnioate"
    // sorted by frequency ascending (http://en.wikipedia.org/wiki/Letter_frequency)
    s = s.toLowerCase().replace(/[^a-z]/g,'')
    for (var i = 0; i < 26; i++)
        if (s.indexOf(letters[i]) < 0) return false
    return true
}

console.log(isPangram("is this a pangram"))  // false
console.log(isPangram("The quick brown fox jumps over the lazy dog"))  // true


(() => {
    "use strict";

    // ----------------- PANGRAM CHECKER -----------------

    // isPangram :: String -> Bool
    const isPangram = s =>
        0 === "abcdefghijklmnopqrstuvwxyz"
        .split("")
        .filter(c => -1 === s.toLowerCase().indexOf(c))
        .length;

    // ---------------------- TEST -----------------------
    return [
        "is this a pangram",
        "The quick brown fox jumps over the lazy dog"
    ].map(isPangram);
})();