为什么我的代码无法识别密码包含字符？

Question

I am making a login form. Before it submits, I check if all the fields are filled in. I also check if the password is longer than 7 characters and contains at least one number, at least one character, and no spaces. My current code keeps on telling me that I am missing a character no matter what I enter. This is the code:

if($("#password").val()==""){

        error += "The password is required.<br>";   

    }
    else if($("#password").val().length<8){

        error += "Your password needs at least 8 characters.<br>";   

    }
    else if($("#password").val().length >= 8){

        var pass = $("#password").val().split("");

        var hasNum = false;

        var hasChar = false;

        var hasSpace = false;

        for(var i = 0; i < pass.length; i++){

            if(pass[i] == " "){

                hasSpace = true;

            }
            else if(Number(pass[i]) == NaN){

                hasChar = true;

            }
            else if(Number(pass[i]) != NaN){

                hasNum = true;

            }


        }

        if(!hasChar){

            error += "Your password must contain at least one character.<br>";

        }
        if(!hasNum){

            error += "Your password must contain at least one number.<br>";

        }
        if(hasSpace){

             error += "Spaces are not allowed in a password.<br>";   

        }

    }

I first check for a space. Then I check if a character can be converted to a number. If not, then it must be a string. If it can be converted, it must be a number. Whatever I type in, it always says "Your password must contain at least one character". How can I fix this? I will give you more code if it is necessary.

Answer 1

The problem is that NaN compares unequal (via ==, !=, ===, and !==) to any other value, including to another NaN value:

NaN === NaN;// false
Number('S') == NaN; //false
Number(10) == NaN; //false

try to use isNaN() instead.