Manage multiple boolean flags

const validatePassword = (password, checkLength, checkUpperCase, checkLowerCase, checkDigit) => {
    // returns `true` or `false`
    // ...
};

const RULE_LENGTH = 1 << 0; // 1
const RULE_UPPER_CASE = 1 << 1; // 2
const RULE_LOWER_CASE = 1 << 2; // 4
const RULE_DIGIT = 1 << 3; // 8

// The default rule should cover all the cases
const RULE_DEFAULT = RULE_LENGTH | RULE_UPPER_CASE | RULE_LOWER_CASE | RULE_DIGIT; // 15

const validatePassword = (password, rule = RULE_DEFAULT) => {};

// Only check the length rule
validatePassword(password, RULE_LENGTH);

// Check length and upper case rules
validatePassword(password, RULE_LENGTH | RULE_UPPER_CASE);

const validatePassword = (password, rule = RULE_DEFAULT) => {
    // `RULE_LENGTH` is enabled
    if (rule & RULE_LENGTH && password.length < 8) {
        return false;
    }

    if (rule & RULE_UPPER_CASE && password === value.toUpperCase()) {
        return false;
    }

    if (rule & RULE_LOWER_CASE && password === value.toLowerCase()) {
        return false;
    }

    if (rule & RULE_DIGIT && password.search(/[0-9]/) < 0) {
        return false;
    }

    return true;
};