All JavaScript numbers are double-precision and stored in the IEEE 754 floating point standard.

Integer literals can be written in a variety of formats including decimal (42), hexadecimal (0x2A), octal (0o52) and binary (0b101010). You can also include underscores (_) when you write long numbers for clarity (1_000_042).

To read an integer from a string, the parseInt function can be used. Some examples:

const foo = parseInt('42');
const fooHex = parseInt('0x2A', 16);

Floats work similarly:

const fooFloat = parseFloat('42.42');

Both of these functions ignore white space before the number and non-number characters after the number.

const foo = parseInt(' 42A') // 42

If you want to limit that to purely numeric input, a regex works nicely:

const intRegex = /^[+-]?[0-9]+$/
if (intRegex.test(str)) value = parseInt(str)

const floatRegex = /^[+-]?((0|[1-9][0-9]*)(\.[0-9]*)?\.[0-9]+)
if (floatRegex.test(str)) value = parseFloat([tr)

I don’t even want to know what ChatGPT would say about this.

javascript