JavaScript趣题：密码验证

var lengthValid = function(pass){  
    return pass.length >= 6;  
};

var contentValid = function(pass){  
    var lowerNum = 0;  
    var upperNum = 0;  
    var numNum = 0;  
    for(var i=0;i<pass.length;i++){  
        var code = pass.charCodeAt(i);  
        if(code >= 48 && code <= 57){  
            numNum++;  
        }  
        else if(code >= 65 && code <= 90){  
            upperNum++;  
        }  
        else if(code >= 97 && code <= 122){  
            lowerNum++;  
        }  
        else{  
            return false;  
        }  
    }  
    return lowerNum && upperNum && numNum;  
};

function validate(password) {  
    return lengthValid(password) && contentValid(password);  
}