# JavaScript parseFloat() function explained with examples

Posted on Mar 07, 2022

Learn how to create a floating-point number using parseFloat() in JavaScript

The JavaScript `parseFloat()` function is a built-in function that returns a floating-point number from the given `string` argument.

The function allows you to extract a `number` from a `string` as shown below:

``````console.log(parseFloat("12.57.a ")); // 12.57
``````

When a number can’t be parsed from the argument, a `NaN` will be returned by the function:

``````console.log(parseFloat("abc ")); // NaN
``````

The `parseFloat()` function can’t adjust the number of digits for the decimal point.

When you need a certain amount of decimal point digits, you need to use the `toFixed()` method.

For example, suppose you only want 2 decimal point digits out of the `string` number. Here’s how you do it:

``````let string = "37.5930"
let float = parseFloat(string);
let fixedFloatString = float.toFixed(2); // "37.59"
let fixedFloat = parseFloat(fixedFloatString);

console.log(fixedFloat); // 37.59
``````

The `parseFloat()` function is called two times because the `toFixed()` method returns a `string` representing the number where you call the function from.

If you don’t need a `number` type representation of the number, you can omit the last `parseFloat()` function call.

# Use isNaN() to check the returned value of parseFloat()

Finally, the `parseFloat()` function returns a `NaN` when the given argument has no valid number representation.

Since a `NaN` isn’t a useful value, you might want to replace it with `0` in some cases.

Consider the following example code:

``````function multiplyByTwo(x) {
if (isNaN(parseFloat(x))) {
x = 0
}
return parseFloat(x) * 2;
}

console.log(multiplyByTwo("abc")) // 0

console.log(multiplyByTwo("3.21`")) // 6.42
``````

When the value of `parseFloat(x)` is `NaN`, the `x` variable will be replaced with `0` instead.

This way, the calculation of `parseFloat(x) * 2` will always return a number `0` in place of `NaN`.

Now you’ve learned how the `parseFloat()` function works in JavaScript. Good work! 😉

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