Metric-Imperial Converter please test

I just finished the Metric-Imperial Converter project.
Please check the program functionality and also the code…

I did not use this function: so I left it blank

this.spellOutUnit = function(unit) {
    var result;
    return result;

I checked some finished code to find why need this function and as I seen this function should give back the full name of units… but I choose completely different way.