Is it possible to parseFloat the whole string?

Question

As you know, the javascript's parseFloat function works only until it meets an invalid character, so for example

parseFloat("10.123") = 10.123
parseFloat("12=zzzz") = 12
parseFloat("z12") = NaN

Is there a way or an implementation of parseFloat that would return NaN if the whole string is not a valid float number?

Answer 1

Use this instead:

var num = Number(value);

Then you can do:

if (isNaN(num)) {
    // take proper action
}

Answer 2

Maybe try:

var f = parseFloat( someStr );
if( f.toString() != someStr ) {
  // string has other stuff besides the number
}

Update: Don't do this, use @dcp's method :)