Zapp and Beyond – JavaScript Framework Thoughts Part 1

Three years ago I was using Backbone and other similar frameworks for the first time… as an experiment I created Zapp, which was a super minimalistic variation on the idea of easy Object instantiation with inheritance, routers/deep linking and custom events. Here is the old repository:

https://github.com/ZevanRosser/Zapp

The source for Zapp is pretty short:

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var Zapp = Zapp ||
function(a, b, c) {
  b = b || {};
  c = c || {};
  if (typeof a != "function") {
    b = a;
    a = Zapp._ctor;
  }
  if (typeof a == "function" && !b.prototype) {
    b.constructor = a;
    a.prototype = b;
    return a;
  } else if (typeof a == "function" && typeof b == "function") {
 
    b.prototype = new a();
    b.prototype.constructor = b;
 
    for (var i in c) {
      b.prototype[i] = c[i];
    }
    b.prototype.proto = a.prototype;
    b.prototype.sup = function() {
      a.apply(this, arguments);
    }
    return b;
  }
  return {};
};
 
Zapp.Object = Zapp;
 
Zapp._ctor = function() {};
 
Zapp.Events = function() {};
 
Zapp.Events.prototype = {
  constructor : Zapp.Events,
  _makeListeners: function() {
    this._listeners = this._listeners || [];
  },
  trigger: function(type, data) {
    this._makeListeners();
    var leng = this._listeners.length;
    for (var i = 0; i < leng; i++) {
      var listener = this._listeners[i];
      if (listener == undefined) continue;
      if (listener.type == type) {
        listener.callback.call(listener.ctx || this, data);
      }
    }
    return this;
  },
  on: function(type, callback, ctx) {
    this._makeListeners();
    this._listeners.push({
      type: type,
      callback: callback,
      ctx: ctx
    });
    return this;
  },
  off: function(type, callback) {
    this._makeListeners();
    for (var i = 0; i < this._listeners.length; i++) {
      var listener = this._listeners[i];
      if (listener == undefined) continue;
 
      if (listener.type == type && (listener.callback == callback || callback == undefined)) {
        this._listeners.splice(i, 1);
      }
    }
    return this;
  },
  allOff: function() {
    this._listeners = [];
    return this;
  }
};
 
// this code needs cleanup
//#path //exact match
//#path/name,name,name // values
//^path // regexp?
Zapp.Router = Zapp(Zapp.Events, function() {
  var self = this;
  if (Zapp.Router._instance) return Zapp.Router._instance;
  Zapp.Router._instance = self;
 
  var prevHash = "";
  var grabHash = /#(.*?)$/;
  var grabTrailingSlash = /\/$/;
 
  function getHash(){
    var hash = window.location.href.match(grabHash);
    return hash ? hash[1] : "";
  }
 
  if (getHash() == ""){
    setTimeout(function(){
      self.trigger("/");
      //self.trigger("change", {hash:"/"});
    }, 2);
 
  }else{
    setTimeout(checkHash, 2); 
  }
 
  function checkHash() {
    var hash = getHash();
    if (prevHash != hash) {
      if (hash == ""){
        self.trigger("/");
        return;
      }
      self.trigger("change", {hash:hash});
      for (var i = 0; i < self._listeners.length; i++) {
        var type = self._listeners[i].type;
        if (type == hash) {
 
          self.trigger(type);
          continue;
        }
        if (hash.match(new RegExp(type))) {
          self.trigger(type);
          continue;
        }
        var names = type.split(",");
        var startsWith = new RegExp("^" + names[0]);
        var starts = hash.match(startsWith);
        if (starts) {
 
          var values = hash.replace(startsWith, "");
 
          values = values.replace(grabTrailingSlash, "");
 
          values = values.substr(1).split("/");
 
          if (names.length - 1 == values.length) {
            var data = {};
 
            for (var j = 1; j < names.length; j++) {
 
              data[names[j]] = values[j - 1];
 
            }
            self.trigger(type, data);
 
          } else {
            continue;
          }
        }
 
      }
      prevHash = hash;
    }
  }
  setInterval(checkHash, 100);
 
}, {
  is: function() {
    this.on.apply(this, arguments);
    return this;
  },
  clear: function() {
    this.off.apply(this, arguments);
    return this;
  },
  clearAll: function() {
    this.allOff.apply(this, arguments);
    return this;
  }
});

The demos for Zapp give you an idea of how it works:

https://github.com/ZevanRosser/Zapp/tree/master/demos

Anyway, I’ve been heavily using Backbone along with Ractive (for templating) these days. And, well, it got me thinking of how I would like this stuff to work if I were to write my own framework. I know I may not use it if I write it, but just like Zapp, it could be interesting to think about again.

The first thing I was thinking about was how frameworks like Ractive and Backbone use get and set methods:

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this.set('someValue', 100);
// or
this.get('someValue);

This enables events to occur when a value on a model or view changes so that a template can update or some other part of your program can update. I thought it would be cool to do something different…

This is really just a first though, but what if properties on an object literal were accompanied by a method that set them – of the same name prefixed by something like a $ or even set and then camel case the property:

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// get a variable like normal:
var myName = obj.person.name;
//set it with the new method:
obj.person.$name('Zevan'); 
// now
obj.person.name = 'Zevan';

With some tweaking I was able to get a prototype of this functionality to work:

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(function() {
 
  if (!Array.isArray) {
    Array.isArray = function(arg) {
      return Object.prototype.toString.call(arg) === '[object Array]';
    };
  }
 
  window.Watch = function(data) {
    this.data = this.process(data);
  };
 
  Watch.prototype = {
    constructor : Watch,
    process : function(obj, keyPath) {
      var path, temp, key;
      keyPath = keyPath ? keyPath + '.' : '';
 
      if(obj === null || typeof(obj) !== 'object') return obj;
 
      temp = obj.constructor(); 
 
      for(key in obj) {
        if(obj.hasOwnProperty(key)) {
          path = keyPath + key;
          temp[key] = this.process(obj[key], path);
          (function(key, path) {
            temp['$' + key] = function(val, silent) {
              temp[key] = val;
              // dispatch some event
              console.log('set', '"' + path + '"', '=', val);
            }; 
            if (Array.isArray(temp[key])){
              temp['$' + key].refresh = function() {
                // dispatch some event
                console.log('refresh collection', path);
              };
            }
          })(key, path);
        }
      }
 
      return temp;
    }
  };
})();

So the way this works is like so:

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var obj = {
  x : 100, 
  y : 100,
  vect : {a : 1, b: 2, c : 3} 
};
 
var w = new Watch(obj);
 
console.log('"x" start value = ', w.data.x); 
 
w.data.$x(2);
 
console.log('"x" is now', w.data.x); 
 
console.log('original "x" is still', obj.x);
 
console.log('------Something Different------');
 
console.log('"vect.a" start value = ', w.data.x); 
 
w.data.vect.$a('I am a!');
 
console.log(w.data.vect.a);

Which will output:

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"x" start value =  100 watch5.html:19
set "x" = 2 watch.js:31
"x" is now 2 watch5.html:23
original "x" is still 100 watch5.html:25
------Something Different------ watch5.html:27
"vect.a" start value =  2 watch5.html:29
set "vect.a" = I am a! watch.js:31
I am a!

So, that’s pretty interesting, and if you JSON.stringify() the object, all the functions get removed which is nice if you need to pass the new JSON off to the server or something.



 
 
 

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