JavaScript
Codes below are:

For my personal research and learning, as well as, for others to be able to learn and understand some of the basic programming skills involved in web development. Below are a few examples of 'JavaScript'. "The" language of all the major Web Browsers on the Internet.

            
                
function range(start, end, step){ 
  if (step == null) step = 1;
  var array = [];
  
  if (step > 0) { 
    for (var i = start; i <= end; i += step)         
      array.push(i);
  } else { 
    for (var i = start; i = end;  i += step)     
      array.push(i); } 
  return array; 
}
 
function sum(array) { 
  var total = 0; 
    for (var i = 0; i < array.length; i++) 
        total += array[i]; 
  return total;     
}
console.log("The sum of the numbers 
1 thru 20 is: " + (sum(range(1,20))));

function factorial(n) {
  if(n == 0) {
  return 1;
  } else {
  return factorial(n - 1) * n;
  }
}
console.log("And it's factorial is: " +     
(factorial(20)));

Results of example JavaScript programs that have been executed, are in the Console below

Learning Web Code