JavaScript · Chapter 20 of 55
JavaScript Number Methods
Numbers have useful methods for formatting and conversion, such as `toFixed()` for decimal places, `toString()` for converting to text, and global functions like `parseInt()` and `parseFloat()`.
The `Number` object also provides static helpers like `Number.isInteger()` and `Number.parseFloat()` for safer type checking.
Formatting numbers
`toFixed(2)` rounds a number to two decimal places and returns it as a string, useful for displaying currency.
Parsing strings to numbers
`parseInt('42px')` returns 42, stopping at the first non-numeric character. `parseFloat('3.14 meters')` returns 3.14.
Example 1 (javascript)
let price = 9.4567;
console.log(price.toFixed(2));Output
9.46toFixed rounds and formats as a string with fixed decimals.
Example 2 (javascript)
console.log(parseInt("42px"));
console.log(parseFloat("3.14 meters"));Output
42
3.14Both parsing functions extract the leading numeric portion.
Key points
- `toFixed(n)` formats a number with n decimal places as a string.
- `parseInt()` and `parseFloat()` extract numbers from strings.
- `Number.isInteger()` checks for whole numbers.
- `Number()` converts a value to a number, or returns NaN if impossible.
💡 Note: toFixed() returns a string, so convert it back with Number() if further math is needed.