Convert boolean result into number/integer

Question

I have a variable that stores false or true, but I need 0 or 1 instead, respectively. How can I do this?

Answer 1

Imho the best solution is:

fooBar | 0

This is used in asm.js to force integer type.

Answer 2

let integerVariable = booleanVariable * 1;

Answer 3

Javascript has a ternary operator you could use:

var i = result ? 1 : 0;

Answer 4

I prefer to use the Number function. It takes an object and converts it to a number.

Example:

var myFalseBool = false;
var myTrueBool = true;

var myFalseInt = Number(myFalseBool);
console.log(myFalseInt === 0);

var myTrueInt = Number(myTrueBool);
console.log(myTrueInt === 1);

You can test it in a jsFiddle.

Answer 5

I just came across this shortcut today.

~~(true)

~~(false)

People much smarter than I can explain:

http://james.padolsey.com/javascript/double-bitwise-not/

Answer 6

When JavaScript is expecting a number value but receives a boolean instead it converts that boolean into a number: true and false convert into 1 and 0 respectively. So you can take advantage of this;

var t = true;
var f = false;

console.log(t*1); // t*1 === 1
console.log(f*1); // f*1 === 0 

console.log(+t); // 0+t === 1 or shortened to +t === 1
console.log(+f); //0+f === 0 or shortened to +f === 0

Further reading Type Conversions Chapter 3.8 of The Definitive Guide to Javascript.