Pangram checker

You are encouraged to solve this task according to the task description, using any language you may know.
A pangram is a sentence that contains all the letters of the English alphabet at least once.

For example:   The quick brown fox jumps over the lazy dog.



Task

Write a function or method to check a sentence to see if it is a   pangram   (or not)   and show its use.



Related tasks

   determine if a string has all the same characters
   determine if a string has all unique characters


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