Error converting string to numeric value

Question

I have a string and I need to convert it to number, in case I need to convert it to a real value, but I’m not getting it. Below is an example where I try to convert the contents of a string into number so they can check.

const valor = parseFloat("109,99").toFixed(2)
console.log(valor, typeof valor)

In addition to not converting the value into a number, the code also returns me the wrong value because it was to return 109.99 instead of 109.00.

Answer 1

What happens is that parseFloat accepts a string in a valid numeric Javascript format. In your case, the string is invalid, since the decimal box separator is a comma. This will cause all characters after it to be ignored. In Javascript, this tab must be a dot.

So before you do the parse of the string, you must ensure that the comma is replaced by a point:

const valor = parseFloat("109,99".replace(',', '.'));
console.log(valor, typeof valor); // 109.99 "number"

Answer 2

The problem is that to turn a value into a float, decimal separator should always be a point instead of a comma.

When you try to convert your string without treating it properly, the result is this:

console.log(parseFloat("109,99")); // Output: 109

In the code you used, the result came with zeros after the point because you were using the method toFixed, displaying numbers after the decimal point of a value.

console.log(parseFloat("5.4372").toFixed(2)) // Output: 5.44

What you can do then to solve the problem, is replace the comma to a point with the method replace before conversion.

See this example below:

var valor = "109,99";
var novo_valor = parseFloat(valor.replace(",", "."));

console.log(novo_valor, "|", typeof novo_valor); // Output: 109.99 | number