code_39.js

// From: http://www.krisbailey.com/2009/01/creating-code-39-barcodes-in-pure-javascript/

function print_html_code39_barcode(
  content,
  height,
  insertCheckDigit,
  printContent,
  fontPointSize,
  thinBarWidth,
  barWidthRatio){
 
  content = content.toUpperCase();
 
  if (isNaN(thinBarWidth)) thinBarWidth = 1;
  if (isNaN(barWidthRatio)) barWidthRatio = 3;
 
  var thin = thinBarWidth;
  var thick = thinBarWidth*barWidthRatio;
  var last = thick*0.66;
 
  var whiteImageURL = 'http://www.krisbailey.com/images/white.gif';
  var blackImageURL = 'http://www.krisbailey.com/images/black.gif';
 
  var thinWhiteBar = "<img src='"+whiteImageURL+"' height='"+height+"' width='"+thin+"'>";
  var thinBlackBar = "<img src='"+blackImageURL+"' height='"+height+"' width='"+thin+"'>";
  var thickWhiteBar = "<img src='"+whiteImageURL+"' height='"+height+"' width='"+thick+"'>";
  var thickBlackBar = "<img src='"+blackImageURL+"' height='"+height+"' width='"+thick+"'>";
  var lastBar = "<img src='"+whiteImageURL+"' height='"+height+"' width='"+last+"'>";
 
  // this is the definition array for what bar
  // combinations correspond to what characters.
  // definition is as follows:
  // 0 = thin white (blank) bar
  // 1 = thin black bar
  // 2 = thick white (blank) bar
  // 3 = thick black bar
  // the 10th digit is for calculating the check digit
  // so, the letter A is:
  // [3,0,1,0,1,2,1,0,3,10]
  // which means:
  //  thick black bar
  //  thin white
  //  thin black
  //  thin white
  //  thin black
  //  thick white
  //  thin black
  //  thin white
  //  thick black
  // and the check digit calculation value is 10
 
  var codes = {
    '0' : [1,0,1,2,3,0,3,0,1,0],
    '1' : [3,0,1,2,1,0,1,0,3,1],
    '2' : [1,0,3,2,1,0,1,0,3,2],
    '3' : [3,0,3,2,1,0,1,0,1,3],
    '4' : [1,0,1,2,3,0,1,0,3,4],
    '5' : [3,0,1,2,3,0,1,0,1,5],
    '6' : [1,0,3,2,3,0,1,0,1,6],
    '7' : [1,0,1,2,1,0,3,0,3,7],
    '8' : [3,0,1,2,1,0,3,0,1,8],
    '9' : [1,0,3,2,1,0,3,0,1,9],
    'A' : [3,0,1,0,1,2,1,0,3,10], // <-- used in the example above
    'B' : [1,0,3,0,1,2,1,0,3,11],
    'C' : [3,0,3,0,1,2,1,0,1,12],
    'D' : [1,0,1,0,3,2,1,0,3,13],
    'E' : [3,0,1,0,3,2,1,0,1,14],
    'F' : [1,0,3,0,3,2,1,0,1,15],
    'G' : [1,0,1,0,1,2,3,0,3,16],
    'H' : [3,0,1,0,1,2,3,0,1,17],
    'I' : [1,0,3,0,1,2,3,0,1,18],
    'J' : [1,0,1,0,3,2,3,0,1,19],
    'K' : [3,0,1,0,1,0,1,2,3,20],
    'L' : [1,0,3,0,1,0,1,2,3,21],
    'M' : [3,0,3,0,1,0,1,2,1,22],
    'N' : [1,0,1,0,3,0,1,2,3,23],
    'O' : [3,0,1,0,3,0,1,2,1,24],
    'P' : [1,0,3,0,3,0,1,2,1,25],
    'Q' : [1,0,1,0,1,0,3,2,3,26],
    'R' : [3,0,1,0,1,0,3,2,1,27],
    'S' : [1,0,3,0,1,0,3,2,1,28],
    'T' : [1,0,1,0,3,0,3,2,1,29],
    'U' : [3,2,1,0,1,0,1,0,3,30],
    'V' : [1,2,3,0,1,0,1,0,3,31],
    'W' : [3,2,3,0,1,0,1,0,1,32],
    'X' : [1,2,1,0,3,0,1,0,3,33],
    'Y' : [3,2,1,0,3,0,1,0,1,34],
    'Z' : [1,2,3,0,3,0,1,0,1,35],
    '-' : [1,2,1,0,1,0,3,0,3,36],
    '.' : [3,2,1,0,1,0,3,0,1,37],
    ' ' : [1,2,3,0,1,0,3,0,1,38],
    '*' : [1,2,1,0,3,0,3,0,1,39],
    '$' : [1,2,1,2,1,2,1,0,1,40],
    '/' : [1,2,1,2,1,0,1,2,1,41],
    '+' : [1,2,1,0,1,2,1,2,1,42],
    '%' : [1,0,1,2,1,2,1,2,1,43]
  };
 
  var tw = 0;
  var sum = 0;
  for (var ee=0; ee<content.length; ee++){
    var tcodes = codes[content.charAt(ee)];
    if (typeof tcodes!='undefined'){
      sum += tcodes[9];
    }
  }
 
  if (insertCheckDigit){
    var checksum = sum%43;
    for (x in codes){
      if (codes[x][9]==checksum){
        content = content+x;
      }
    }
  }
 
  content = '*'+content+'*';
 
  var htmlout = "<"+"table border='0' cellpadding='1' cellspacing='1'>";
  htmlout += "<"+"tr><"+"td align='center'><nobr>";
 
  for (var i=0; i<content.length; i++){
    tcodes = codes[content.charAt(i)];
    if (typeof tcodes!='undefined'){
      for (var xi=0; xi<9; xi++){
        switch (tcodes[xi]){
          case 0:
            htmlout += thinWhiteBar;
          break;
          case 1:
            htmlout += thinBlackBar;
          break;
          case 2:
            htmlout += thickWhiteBar;
          break;
          case 3:
            htmlout += thickBlackBar;
          break;
        }
      }
    }
    htmlout += lastBar;
  }
 
  htmlout += "</nobr><"+"/td><"+"/tr>";
 
  if (printContent){
    htmlout += "<"+"tr><"+"td align='center' style='font-size: "+fontPointSize+"pt;'>";
    htmlout += "<nobr>"+content+"</nobr><"+"/td><"+"/tr>";
  }
 
  htmlout += "<"+"/table>";
  return htmlout;
}

/*

Arguments:

content - This is the string you want to have encoded
height - The height in pixels of the barcode
insertCheckDigit - true or false, whether to insert a check digit or not
(not needed for most scanners)
printContent - true or false, whether or not to print the content string below the barcode
fontPointSize - The size of the font to use if printing the content
thinBarWidth - The width in pixels of thin bars, default is 1
barWidthRatio - The ratio of thin to thick bar widths. A good value of 2.8-3.0, default is 3


Use:

Include the javascript function in your page somehow, then you can do something as simple as:
<script type="text/javascript">
document.write(print_html_code39_barcode('this is a barcode', 30, false, true, 8));
</script>

*/