A JavaScript function for converting a number from binary to decimal.

binaryToDecimal.js

/*********************************************************
 *  Converts a positive integer from binary to decimal.
 *  @param {Number} binaryNumber (e.g. 1101)
 *  @return {Number} decimalNumber (e.g. 13)
 ********************************************************/
 function binaryToDecimal( binaryNumber ) {
        
   // decimalNumber represents a summation of digit values.
   var decimalNumber = 0;

   // placeValue represents a power of two.
   var placeValue = 1;

   // Compute each digit value (from right to left).
   while ( binaryNumber > 0 ) {

     // Divide binaryNumber by 10. Store the decimal remainder.
     var remainder = binaryNumber % 10;

     // Determine the remainder digit.
     var digitValue = remainder * placeValue;

     // Add the digitValue to the decimalNumber sum.
     decimalNumber = decimalNumber + digitValue;

     // Increment the placeValue
     placeValue *= 2;

     // Increment to the next digit (left adjacent).
     binaryNumber = Math.floor( binaryNumber / 10 );
   }

   // Return the sum of digit values.
   return decimalNumber;
 }