pojs

pojs

backbone@next implemented with plain old javascript with minimal dependencies

documentation

Callback

Callback is the event system in pojs. it is used for module-to-module or module-to-collection communication

on

Callback.on(event, callback, [context])

Bind a callback function to an object. The callback will be invoked whenever the event is fired. If you have a large number of different events on a page, the convention is to use colons to namespace them: "poll:start", or "change:selection".

off

Callback.off([event], [callback], [context])

Remove a previously-bound callback function from an object. If no context is specified, all of the versions of the callback with different contexts will be removed. If no callback is specified, all callbacks for the event will be removed. If no event is specified, callbacks for all events will be removed.

trigger

Callback.trigger(event, [*args])

Trigger callbacks for the given event. Subsequent arguments to trigger will be passed along to the event callbacks.

Collection

purpose of collection

• cache data on client side
• network communication
• communication channel between modules

initialiazation

new Collection([seed], [name], [options])

Collections are ordered sets of models.

seed (array of object)

inital data to populate collection

name (string)

prefix of localstorage key, if absent collection wont be saved to localstorage

options (object)

define options.idAttr to override the default id index key define options.ajax to override the default ajax network request function use by collection define options.cache to override the default localstorage cache function

extending collection

Collection constructor only process the first one arguments (seed), addtional arguments are processed by Collection.init function.

the default init function

init:function(name, opt){
	this.name = name
	opt = opt || {}
	this.ajax = opt.ajax || this.ajax
	this.idAttr = opt.idAttr || this.idAttr
}

collection only cache the data if name is a valid string

Collection.init can be overriden by extend function or inherit keyword

// in customcollection.js
const Collection = require('po/collection')

Collection.extend({
	init:function(jwt){
		this.name = 'CustomColl'
		this.idAttr = '_key'
		this.ajax = function(method,route,params,cb){
			if (!route) return cb(null,params)
			pico.ajax(method,route,params,{Authorization: 'Bearer' + jwt},function(err,state,res){
				if (4!==state) return
				if (err) return cb(err)
				try{var obj=JSON.parse(res)}
				catch(ex){return cb(ex)}
				cb(null,obj)
			})
		}
		return true
	}
})

// in another.js
const CustomCollection = require('customcollection')

const coll = new CustomCollection(null, {}, jwt); // name, opt arguments are no longer needed in CustomerCollection

override ajax function

if the default ajax function doesn't meet your requirement, for example you need addtional headers. you can override it by passing in a new ajax function

// pico is already defined

function aclosure(jwt){
  const options = {
    headers: {
      'Content-Type': 'application/json',
      Authorization: 'Bearer ' + jwt
    }
  }
  return {
    ajax(method, route, params, cb){
      if (!route) return cb(null,params)
      pico.ajax(method,route,params,options,function(err,state,res){
        if (4!==state) return
        if (err) return cb(err)
        try{var obj=JSON.parse(res)}
        catch(ex){return cb(ex)}
        cb(null,obj)
      })
    }
  }
}

const coll = new Collection(null, {}, 'example', aclosure(jwt));

events

Collection has Callback built in. These are the events supported

• add: when new model added to collection
• update: when an existing model got updated
• delete: when an existing model got deleted
• clear: when the collection got cleared

Example

// in amodule.js

// newModel will be trigger 2 times
function newModel(coll, id){
	// this === amodule instance
}

return {
	start(opt, coll){
		coll.on('add', newModel, this)
		coll.create({id: 1, value: 'a'})
		coll.create({id: 2, value: 'b'})
	}
}

load

collection.add(models, cb)

Add an array of raw object to the collection, firing an "add" event for each object added to collection as model

const coll = new Colection()
coll.create({id: 1, value: 'a'})

list

collection.list([filter1], [filter2], cb)

Get all models from a collection. only read from local storage if no filter1 and filter2 passed in

you can specified startId and lastId as filter1 and filter2, list will return an array models which id in (startId, lastId). list will trigger network call to upstream to get missing models in local storage

collection.list(1, 100, () => {})

you can also specified array of need id as filter1, list will return an array models which id in filter1. list will trigger network call to upstream to get missing models in local storage

collection.list(['dog', 'cat'], () => {})

module

extending a module

There are two ways to extend a module

• use the extend built in method
• use inherit keyword, it is synxtax sugar of require + extend inherit is more convenient but .extend is more flexible it allow you to extend multiple objects in a file

Example:

// CustomModule.js
const Module = require('po/module');

return Module.extend({
	start(opt, param1){
		Module.prototype.start.call(this, opt);
		
		// extra processing here
	}
});

// othermodule.js
const CustomModule = inherit('CustomModule')

return {
	start(opt, param1){
		CustomModule.prototype.start.call(this, opt, param1);
	}
}

events

Module has Callback builtin to support event communication between modules

Example

// module1.js
function onHello(data){
	console.log(data) // 'abc'
}
function onWorld(data){
	console.log(data) // 'def'
}
return {
	start(opt, mod2){
		this.peer = mod2
		mod2.callback.on('hello', onHello, this)
		this.callback.on('world', onWorld, this)
	},
	go(){
		this.peer.callback.trigger('foo', 123)
		this.callback.trigger('bar', 456)
	}
}

// module2.js
function onFoo(data){
	console.log(data) // 123
}
function onBar(data){
	console.log(data) // 456
}
return {
	start(opt, mod1){
		this.peer = mod1
		mod1.callback.on('bar', onBar, this)
		this.callback.on('foo', onFoo, this)
	},
	go(){
		this.peer.callback.trigger('world', 'def')
		this.callback.trigger('hello', 'abc')
	}
}

// in parent of module1 and module2
const m1 = new Module1
const m2 = new Module2
m1.start(null, m2)
m2.start(null, m1)
m1.go()
m2.go()

test

load test/test.html in browser, result is in console panel