How do I pass a binary literal to JavaScript eval?

Question

Before I start, please don't tell me not to use eval; I know the input is perfectly sanitary, so it's safe, fast, and easy.

I'm using a JavaScript engine to power a calculator I've written in Java. To do this, I simply concatonate input into a string and pass it to JavaScript. For instance, clicking the buttons 1, +, and 5 results in building the String "1+5". I got this working for hexadecimal, too, by putting 0x before the letters, so A, +, and 8 gives me "0xA+8. My problem comes from programming its binary mode. I tried passing it 0b1101+0b10 (which is how Java does binary literals), but it just throws an error. How do I handle binary literals in JavaScript?

Answer 1

Update: As of ES2015, JavaScript supports binary Number literals:

console.log(0b1101+0b10) // 15 (in decimal)

Alternatively, you can use a string, and use Number.parseInt with a base of 2:

var a = parseInt('1101', 2) // Note base 2!
var b = parseInt('0010', 2) // Note base 2!
console.log(a+b) // 15 (in decimal)

For displaying numbers in different bases, Number#toString also accepts a base:

(15).toString(2) // 1111

Note: If passing user input directly to eval(), use a regex to ensure the input only contains numbers and the operators you expect (+, -, etc).