How can I check if a string is a float?

Question

I am passing in a parameter called value. I'd like to know if value is a float. So far, I have the following:

if (!isNaN(value)) {     alert('this is a numeric value but not sure if it is a float.'); } 

How do I go one step further and convert the string to something that can evaluate to a float?

Answer 1

Like this:

if (!isNaN(value) && value.toString().indexOf('.') != -1) {     alert('this is a numeric value and I\'m sure it is a float.'); }​ 

Answer 2

You can use the parseFloat function.

If the value passed begins with what looks like a float, the function returns the value converted to a float, otherwise it will return NaN.

Something like:

function beginsWithFloat(val) {   val = parseFloat(val);   return ! isNaN(val); } console.log(beginsWithFloat("blabla")); // shows false console.log(beginsWithFloat("123blabla")); // shows true