Question

// convert the number to it's standard value (kilogram)
standard  = parseFloat(unit / from);
// now convert it to the new measurement unit
converted = parseFloat(standard * eval(to));

http://jsfiddle.net/zeByX/23/

If you enter a number less than one, for example ‘0.234234234’ and try converting to a new unit by changing the drop-down. Any number less than 1 and it’ll go to zero.

Any idea what is going on here?

Answer 1

Although the error is caused because of the usage of parseInt() where you should have used parseFloat(), there’s a whole lot more wrong with your code.

• eval() is evil, and you’re using it where you don’t even need it or could easily replace it with a far better solution.
  • eval(to) is unnecessary since to is already a number.
  • In the other cases, eval is used to use a string to access a global variable. This is a very bad idea, and it’s much more appropriate to store your unit/value mappings in an object literal, such as var units = { gram: 1000, kilogram: 1, ... } Then, you can access the value by simply using the string as index, such as unit["milligram"].
• You don’t need parseFloat() when you already have a number, such as with unit / from or standard * to)
• All your variable declarations (except from from) in the function are global, because you’re missing the var keyword in front.

Here’s a somewhat “fixed” fiddle.