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 pangram(k:string):Boolean {
  var lowerK:String = k.toLowerCase();
  var has:Object = {}
 
  for (var i:Number=0; i<=k.length-1; i++) {
    has[lowerK.charAt(i)] = true;
  }
 
  var result:Boolean = true;
 
  for (var ch:String='a'; ch <= 'z'; ch=String.fromCharCode(ch.charCodeAt(0)+1)) {
      result = result && has[ch]
  }
 
  return result || false;
}