Type conversion of Boolean to Number in JavaScript

Question

I was working on type conversion of Boolean values to Number in javascript.

console.log(new Number(true));//Prints 1
console.log(+true);//Prints 1
console.log(pa         


        

Answer 1

If you are actually working on number conversions then this table might be very helpful:

Answer 2

Number constructor invokes toNumber internally which as per spec

Boolean - Return 1 if argument is true. Return +0 if argument is false.

Which means Number(true) returns 1.

However, parseInt invokes toString internally and as per spec

Boolean
If argument is true, return "true".

If argument is false, return "false".

Which means parseInt(true) -> parseInt("true") -> NaN

since as per spec again

3. If number is NaN, +0, −0, +∞, or −∞, return +0.

Hope this helped.

Answer 3

Because parseInt expects a string and 'true' is NaN.

From MDN:

parseInt()

The parseInt() function parses a string argument and returns an integer of the specified radix (the base in mathematical numeral systems).