Function to parse floats optionally followed by %, more strict than parseFloat in javascript
I think it's a bit too much code. If you are already using a regular expression, why not using it to do all the parsing for you?

function parseNumeric(number) {
    var num = number.trim();
    var reOut = /^([-+]?(\d+\.?\d*|\d*\.?\d+))\s*%?$/.exec(num);
    return reOut ? parseFloat(reOut[1]): undefined;
}