SOURCE

var mySqrt = function(x) {
    if(x === 1){
        return 1
    }
    let max = x
    let min = 0;
    while(max - min > 1){
        let m = parseInt((max + min) / 2)
        if(x/m < m){
            max = m
        }else{
            min = m
        }
    }
    return min
};
console.log(mySqrt(5))