JavaScript Square Root Function

/*
 * Why are there two `temp`s? Otherwise, it will repeat forever for some numbers.
 * With a single `temp`, sqrt(3) with infinitely iterate between 1.7320508075688772 and 1.7320508075688774
 */
function sqrt(x){
    let temp,
    temp2,
    i=2*x/(x+1);
    while(temp != i && temp2 != i){
        temp2 = temp;
        temp = i;
        i = (i**2 + x)/(2*i)
    }
    return i
}

// It may seem like I stole this from pastebin.com/umyk7xVB but trust me, this is mine.