What is the difference between y=""; y=x%2+y; x=Math.floor(x/2); and y+=x%2

Question

function z(x)
{
var y="";
while (x>0){
y = x%2 + y;
x = Math.floor ( x/2);
}
return y}

I cant understand how this function outputs the binary code of x.
if I write first way it outputs 1010 for x=10:
if the second way it outfuts 0101.
how it happens?

Answer 1

They are exactly opposed:
y = x%2 + y;
y+=x%2; is equals to y= y + x%2
BUT you handling strings then order is important here (differently by numbere where x+y and y+x get same result)
If you have asking why you have handling string, well when you add a string with another type var this var is converted to string for make operation

Answer 2

it will ofcource give binary as the method is to get binary is get the remainder of number by moduling 2 and after divide by 2 until num==0.. there is no need of Math.floor directly divide /x/2