Determining a pangram string in JavaScript

Pangram strings:

A pangram is a string that contains every letter of the English alphabet.

We are required to write a JavaScript function that takes in a string as the first and the only argument and determines whether that string is a pangram or not. For the purpose of this problem, we will take only lowercase alphabets into consideration.

Example

The code for this will be −

 Live Demo

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 < length; i++){       const el = str[i];       const index = alphaArr.indexOf(el);       if(index !== -1){          alphaArr.splice(index, 1);       };    };    return !alphaArr.length; }; console.log(isPangram(str));

Output

And the output in the console will be −

true