Negative numbers to binary string in JavaScript

Question

Anyone knows why javascript Number.toString function does not represents negative numbers correctly?

//If you try
(-3).toString(2); //shows \"-11\"
// but if         


        

Answer 1

Short answer:

1. The toString() function takes the decimal, converts it to binary and adds a "-" sign.

2. A zero fill right shift converts it's operands to signed 32-bit integers in two complements format.

A more detailed answer:

Question 1:

//If you try
(-3).toString(2); //show "-11"

It's in the function .toString(). When you output a number via .toString():

Syntax

numObj.toString([radix])

If the numObj is negative, the sign is preserved. This is the case even if the radix is 2; the string returned is the positive binary representation of the numObj preceded by a - sign, not the two's complement of the numObj.

It takes the decimal, converts it to binary and adds a "-" sign.

1. Base 10 "3" converted to base 2 is "11"
2. Add a sign gives us "-11"

Question 2:

// but if you fake a bit shift operation it works as expected
        (-3 >>> 0).toString(2); // print "11111111111111111111111111111101"

A zero fill right shift converts it's operands to signed 32-bit integers. The result of that operation is always an unsigned 32-bit integer.

The operands of all bitwise operators are converted to signed 32-bit integers in two's complement format.