JavaScript data_javascript スキルの双方向バインディングを簡単に実装

function DataBinder(object_id){
  // Use a jQuery object as simple PubSub
  var pubSub=jQuery({});

  // We expect a `data` element specifying the binding
  // in the form:data-bind-<object_id>="<property_name>"
  var data_attr="bind-"+object_id,
    message=object_id+":change";

  // Listen to chagne events on elements with data-binding attribute and proxy
  // then to the PubSub, so that the change is "broadcasted" to all connected objects
  jQuery(document).on("change","[data-]"+data_attr+"]",function(eve){
    var $input=jQuery(this);

    pubSub.trigger(message,[$input.data(data_attr),$input.val()]);
  });

  // PubSub propagates chagnes to all bound elemetns,setting value of
  // input tags or HTML content of other tags
  pubSub.on(message,function(evt,prop_name,new_val){
    jQuery("[data-"+data_attr+"="+prop_name+"]").each(function(){
      var $bound=jQuery(this);

      if($bound.is("")){
        $bound.val(new_val);
      }else{
        $bound.html(new_val);
      }
    });
  });
  return pubSub;
}

function User(uid){
  var binder=new DataBinder(uid),
    
    user={
      attributes:{},
      // The attribute setter publish changes using the DataBinder PubSub
      set:function(attr_name,val){
        this.attributes[attr_name]=val;
        binder.trigger(uid+":change",[attr_name,val,this]);
      },

      get:function(attr_name){
        return this.attributes[attr_name];
      },
    
      _binder:binder
    };

  // Subscribe to PubSub
  binder.on(uid+":change",function(evt,attr_name,new_val,initiator){
    if(initiator!==user){
      user.set(attr_name,new_val);
    }
  });

  return user;
}

// javascript 
var user=new User(123);
user.set("name","Wolfgang");

// html
<input type="number" data-bind-123="name" />

function DataBinder( object_id ) {
 // Create a simple PubSub object
 var pubSub = {
  callbacks: {},

  on: function( msg, callback ) {
   this.callbacks[ msg ] = this.callbacks[ msg ] || [];
   this.callbacks[ msg ].push( callback );
  },

  publish: function( msg ) {
   this.callbacks[ msg ] = this.callbacks[ msg ] || []
   for ( var i = 0, len = this.callbacks[ msg ].length; i < len; i++ ) {
    this.callbacks[ msg ][ i ].apply( this, arguments );
   }
  }
 },

 data_attr = "data-bind-" + object_id,
 message = object_id + ":change",

 changeHandler = function( evt ) {
  var target = evt.target || evt.srcElement, // IE8 compatibility
    prop_name = target.getAttribute( data_attr );

  if ( prop_name && prop_name !== "" ) {
   pubSub.publish( message, prop_name, target.value );
  }
 };

 // Listen to change events and proxy to PubSub
 if ( document.addEventListener ) {
  document.addEventListener( "change", changeHandler, false );
 } else {
  // IE8 uses attachEvent instead of addEventListener
  document.attachEvent( "onchange", changeHandler );
 }

 // PubSub propagates changes to all bound elements
 pubSub.on( message, function( evt, prop_name, new_val ) {
var elements = document.querySelectorAll("[" + data_attr + "=" + prop_name + "]"),
  tag_name;

for ( var i = 0, len = elements.length; i < len; i++ ) {
 tag_name = elements[ i ].tagName.toLowerCase();

 if ( tag_name === "input" || tag_name === "textarea" || tag_name === "select" ) {
  elements[ i ].value = new_val;
 } else {
  elements[ i ].innerHTML = new_val;
 }
}
 });

 return pubSub;
}

// In the model's setter:
function User( uid ) {
 // ...

 user = {
  // ...
  set: function( attr_name, val ) {
     this.attributes[ attr_name ] = val;
     // Use the `publish` method
     binder.publish( uid + ":change", attr_name, val, this );
  }
 }

 // ...
}