javascript lessons

cool.js

var groups =_.groupBy(categories, _.curry(_.has)(_, 'id'));

inheritance.js

// Root class
var ElasticQuery = function () {
};

module.exports = ElasticQuery;

// Subclass 1
var ElasticQuery = require('./elasticQuery');

var ElasticReportQuery = function () {
    this.excludeInvalidEvents();
    this.aggs = {
        "cost": {
            "sum": { "field": "cost" }
        },
        "type": {
            "terms": { "field": "typeName"}
        }
    }
    this.aggs.unique_users = this.getUniqueUsersQuery();
    return this;
};

ElasticReportQuery.prototype = new ElasticQuery();

module.exports = ElasticReportQuery;


// Subclass 2
var ElasticQuery = require('./elasticQuery');

var ElasticEventQuery = function () {
    this.excludeInvalidEvents();
    return this;
};

ElasticEventQuery.prototype = new ElasticQuery();

module.exports = ElasticEventQuery;


// Another way in node
var CampaignConfigController = function () {
  // ...
}

CampaignConfigController.prototype.aFunction = function() {
  // ...
}

util.inherits(CampaignConfigController, BaseController);

module.exports = CampaignConfigController;

javascript_enum.js

// Example of a enum-like class in javascript

var WeekDays = function () {
    // This could be regarded as a constructor
    // We cannot fit this into the prototype since "elements2 would be shared accross different instances
    this.elements = {
        MONDAY: {name: "mon", index: 1},
        TUESDAY: {name: "tue", index: 2},
        WEDNESDAY: {name: "wed", index: 3},
        THURSDAY: {name: "thu", index: 4},
        FRIDAY: {name: "fri", index: 5},
        SATURDAY: {name: "sat", index: 6},
        SUNDAY: {name: "sun", index: 7}
    }
};

WeekDays.prototype = {
   
   // This is the interface of the class
   
    nameFromIndex: function (index) {
        return this.elements[index].name;
    },

    wholeWeekInexes: function () {
        return this.elements.map(function (day) {
            return day.index;
        });
    }
}

module.exports = WeekDays;