var min=8;
var max=18;

// Function that turns a collection into an array so array operations can be performed on data.
function collectionToArray(col)
{
	a = new Array();
	for (i=0;i<col.length;i++)
	{
		a[a.length] = col[i];
	}
	return a;
}


// Funtion to add more data to an existing array from a collection.
function concatColToArray(arr, col)
{
	for (i=0;i<col.length;i++)
	{
		arr[arr.length] = col[i];
	}
	return arr;
}

// Simple genertic font size change operation, based on element ID and size.
function ChangeFontSize(id, size) {
	document.getElementById(id).style.fontSize = size + "px";
}

// Function to Enlarge the font size on the common elements on a page.
// note the A, SPAN, and P tags.
function increaseFontSize() {
   var tags = collectionToArray(document.getElementsByTagName('a'));
   tags = concatColToArray(tags,document.getElementsByTagName('span'));
   tags = concatColToArray(tags,document.getElementsByTagName('p'));
   tags = concatColToArray(tags,document.getElementsByTagName('td'));

   for(i=0;i<tags.length;i++) {
      if(tags[i].style.fontSize) {
         var s = parseInt(tags[i].style.fontSize.replace("px",""));
      } else {
         var s = 12;
      }
      if(s!=max) {
         s += 1;
      }
      tags[i].style.fontSize = s+"px"
   }
}

// Function to Shrink the font size on the common elements on a page.
// note the A, SPAN, and P tags.
function decreaseFontSize() {
   var tags = collectionToArray(document.getElementsByTagName('a'));
   tags = concatColToArray(tags,document.getElementsByTagName('span'));
   tags = concatColToArray(tags,document.getElementsByTagName('p'));
   tags = concatColToArray(tags,document.getElementsByTagName('td'));

   for(i=0;i<tags.length;i++) {
      if(tags[i].style.fontSize) {
         var s = parseInt(tags[i].style.fontSize.replace("px",""));
      } else {
         var s = 12;
      }
      if(s!=min) {
         s -= 1;
      }
      tags[i].style.fontSize = s+"px"
   }   
}