Javascript: Add two binary numbers (returning binary)

Question

I have two inputs in binary, and I'm returning the addition result in binary as well.

var addBinary = function(a, b) {
    var dec = Number(parseInt(a, 2)) + Number(parseInt(b, 2));
    return dec.toString(2);
};

For some insanely big binary like

a = 10100000100100110110010000010101111011011001101110111111111101000000101111001110001111100001101

b = 110101001011101110001111100110001010100001101011101010000011011011001011101111001100000011011110011

I'm outputting

110111101100010011000101110110100000011101000101011000000000000000000000000000000000000000000000000

where the supposed correct output is

110111101100010011000101110110100000011101000101011001000011011000001100011110011010010011000000000

Is it because of overflow? If so, what are the restrictions in Javascript for binary addition overflow? Sorry for the bunch of 1's and 0's.

Answer 1

instead of dealing with binary, we can convert them to decimal numbers and perform any arithmetic operation then convert back to binary again.

function calculateBinary(expr){
    let [pre,post]=expr.split(/[+|\-|\*|\/]/).map(binary=>parseInt(parseInt(binary, 2).toString(10).trim()));
    let sign=expr.match(/[+|\-|\*|\/]/)[0];
    let res=eval(pre+sign+post);
    return res.toString(2);
}
console.log(calculateBinary('11011+1000'))//=>100011
console.log(calculateBinary('1000-0100'))//=>100
console.log(calculateBinary('1000/0100'))//=>10
console.log(calculateBinary('10*10'))//=>100