A Pen by Andrew Kirchmyer.

script.js

var validator = {
    types: {},
    messages: [],
    config: {},
    
    // the interface method. data should be an object
    validate: function(data){
        var i, msg, type, checker, result_ok;
        
        // reset all messages
        this.messages = [];
        
        for (i in data) {
            if (data.hasOwnProperty(i)) {
                type = this.config[i];
                checker = this.types[type];
                
                if (!type) {
                    continue; // no need to validate data
                }
                
                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);
                }
                
            } //hasOwnProperty
        } //for
        return this.hasErrors();
    }, //validator.validate()
    hasErrors: function() { //helper
        return this.messages.length !== 0;
    }
}; //validator

validator.types.isNonEmpty = {
    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 letters and numbers"
};

validator.config = {
    first_name: 'isNonEmpty',
    age: 'isNumber',
    username: 'isAlphaNum'
}

var data = {
    first_name: "",
    last_name: "Kirchmyer",
    age: "unknown",
    username: "o_0"
};

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

strategy-pattern.markdown

strategy pattern

A Pen by Andrew Kirchmyer on CodePen.

License.