'-' or '+' will pass test of isFloat?

[robberfree]

I found

isFloat('-')//true
isFloat('+')//true

but

toFloat('-')//NaN
toFloat('+')//NaN

maybe it's a bug?

[robberfree]

@linkinmedo thanks a lot.
maybe better to promote this line

if (str === '' || str === '.' || str === '-' || str === '+') {
    return false;
  }

then we can tell user the test result quickly without building a new RegExp.
thanks again.