Random Password Generate

When we develop any application, we need a random password for every user.As more as secure password is recommended. The conditions for secure password must follow

1. Minimum 8 character long password
2. Minimum one uppercase letter
3. Minimum one lowercase letter
4. Minimum one special character
5. Minimum one number.

The combination of above condition will generate a secure password.

function generatePassword(length) {
    // code to generate passowrd
    var charNum = "0123456789";
    var charLower = "abcdefghijklmnopqrstuvwxyz"
    var charUpper = "ABCDEFGHIJKLMNOPQRSTUVWXYZ"
    var charSpecial = "!@#$%^&*_"
    var charAll = charNum + charLower + charUpper + charSpecial;
    var password = "";
    for (var i = 0; i < length; i++) {
        if (i == 0) {
            password += charUpper.charAt(Math.floor(Math.random() * charUpper.length));
        }
        if(i == 1){
            password += charLower.charAt(Math.floor(Math.random() * charLower.length));
        }
        if(i == 2){
            password += charNum.charAt(Math.floor(Math.random() * charNum.length));
        }
        if(i == 3){
            password += charSpecial.charAt(Math.floor(Math.random() * charSpecial.length));
        }
        var char = charAll[Math.floor(Math.random() * charAll.length)];
        password += char;
    }
    return password;
}