Get Decimal Float Number

Reference:

  1. http://blog.xuite.net/chingwei/blog/20942533-%E3%80%90%E7%A8%8B%E5%BC%8F%E3%80%91JS+%3A+%E5%B0%8F%E6%95%B8%E9%BB%9E%E7%AC%ACN%E4%BD%8D%E5%9B%9B%E6%8D%A8%E4%BA%94%E5%85%A5
  2. http://www.w3schools.com/jsref/jsref_tofixed.asp
  3. http://stackoverflow.com/questions/6134039/format-number-to-always-show-2-decimal-places