Did you know that regexp matches:

• -
• 1.

But fails to match:

• .1
• -.1

You might want to try this. It's somewhat simpler than yours, and it disallows the single hyphen, but allows decimals which start with the decimal point and no preceding 0.

/^[-]?(?:[.]\d+|\d+(?:[.]\d*)?)$/
[download]

Or if you consider a leading/trailing decimal point to be an error, it can be made simpler:

/^[-]?\d+(?:[.]\d+)?$/
[download]