# parseFloat function

The `parseFloat` function converts a string to a floating point number. This is necessary for values like `'12.5px'` - when the first there is a number, and then units of measurement. If you apply the `parseFloat` function to `'12.5px'`, the result will be the number `12.5` (and it will really be a number, not a string). The conversion will only occur if the integer is at the beginning of the string, otherwise `NaN` will be displayed. You can set a number system of a number as a second optional parameter, and the function will return the number converted from the specified number system to decimal.

## Syntax

`parseFloat(string, [number system]);`

## Example

Let's extract a fractional number from the beginning of a string:

`console.log(parseFloat('10.3px'));`

The code execution result:

`10.3`

## Example

In this example, the function will not be able to read the number (because it is not at the beginning of the string) and will return `NaN`:

`let str = 'width: 100px'; console.log(parseFloat(str));`

The code execution result:

`NaN`

## See also

- the `parseInt` function
  that extracts an integer from the beginning of a string
- the `Number` function
  that converts to a number

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