Strategy pattern

secondary.js

    var data = {
        first_name: "Vladimir",
        last_name: "Sljubura",
        age: "unknown",
        username: "Slju"
    };

    validator.config = {
        first_name: 'required',
        age: 'numeric',
        username: 'alpha'
    };

    validator.validate(data);
    if (validator.hasErrors()) {
        console.log(validator.messages.join("\n"));
    }

    validator.types.inNonEmpty = {
        validate: function (value) {
            return value !== "";
        },
        instructions: "the value cannot be empty"
    };
    validator.types.isNumber = {
        validate: function (value) {
            return !isNaN(value);
        },
        instructions: "the value can only be a valid number"
    };
    validator.types.isAlphaNum = {
        validate: function (value) {
            return !/[^a-z0-9]/i.test(value);
        },
        instructions: "the value can only contain characters and numbers, no special symbols"
    };

    var validator = {

        types: {},

        messages: {},

        config: {},

        validate: function (data) {

            var i, msg, type, checker, result_ok;

            this.messages = [];

            for (i in data) {

                if (data.hasOwnProperty(i)) {

                    type = this.config[i];
                    checker = this.types[type];

                    if (!type) {
                        continue;
                    }
                    if (!checker) {
                        throw {
                            name: "ValidationError",
                            message: "No handler to validate type " + type
                        };
                    }
                    result_ok = checker.validate(data[i]);
                    if (!result_ok) {
                        msg = "Invalid value for *" + i + "*, " + checker.instructions;
                        this.messages.push(msg);
                    }

                }

            }
            return this.hasErrors();

        },
        hasErrors: function () {
            return this.messages.length !== 0;
        }

    };