JavaScript functions for validating user input for a base converter applet.

sanityChecks.js

/*********************************************************
 * Removes space characters from the input string.
 * Sets any letters in the input string to uppercase.
 * @param {String} inputString
 * @return {String} "cleaned up" inputString.
 *********************************************************/
function sanitizeInput( inputString ) {

    // If the inputString is empty, return an error.
    if (!inputString) return "Error";

    // Remove space characters.
    var modifiedString = "";
    for (var i in inputString) 
      if (inputString[i] != " ")
        modifiedString += inputString[i];

    // Set letters to uppercase. Return result.
    return modifiedString.toUpperCase();
}

/*********************************************************
 * Checks whether a given string represents a number of
 * the given base. For example, 1101 is base 2. 
 * @param {String} digitString 
 * @param {String} base 
 * @return {Boolean} true if digitString matches base
 ********************************************************/
function numberAndBaseMatch( digitString, base ) {

    // Determine the cardinality of the digitSet.
    var digitSet = ['0'];
    var letterDigits = ['A','B','C','D','E'];
    for (var i = 2; i <= 16; i++) {

      // Add digits 0 through 9 as needed.
      if (i <= 10) {
        digitSet.push( (i - 1).toString().charAt(0) );
        if (parseInt(base) == i) break;
      }

      // Add digits A through F as needed.
      else {
        digitSet.push( letterDigits[i - 11] );
        if (parseInt(base) == i) break;       
      }
    }

    // Check whether inputString chars are digitSet members.
    for (var i in digitString) {
      var charMatch = false;
        for (var k in digitSet) {
          if (digitString[i] == digitSet[k]) charMatch = true;
        }
        if (!charMatch) return false;
    }

    // Return true if inputString matches inputBase.
    return true;
}

/*********************************************************
 * Displays an output message on the webpage.
 * @param {String} message to display
 ********************************************************/
function displayResult( message ) {
  var resultArea = document.getElementById("resultArea");
  var content = ("<h4><em>" + message + "</em></h4>");
  resultArea.innerHTML = content;
  resultArea.style.display = "block";
}