jQuery call plugin method from inside callback function - javascript

I am using a boilerplate plugin design which looks like this,
;(function ( $, window, document, undefined ) {
var pluginName = "test",
defaults = {};
function test( element, options ) {
this.init();
}
test.prototype = {
init: function() {}
}
$.fn.test = function(opt) {
// slice arguments to leave only arguments after function name
var args = Array.prototype.slice.call(arguments, 1);
return this.each(function() {
var item = $(this), instance = item.data('test');
if(!instance) {
// create plugin instance and save it in data
item.data('test', new test(this, opt));
} else {
// if instance already created call method
if(typeof opt === 'string') {
instance[opt].apply(instance, args);
}
}
});
};
})( jQuery, window, document );
Now say i have two <div> with same class container.
And now i would call my test plugin on these divs like so,
$(".container").test({
onSomething: function(){
}
});
Now when function onSomething is called from inside my plugin how can i call that plugin public methods referring to the instance onSomething function was called from?
For example something happened with the first container div and onSomething function was called for only first container div.
To make it a bit more clear I have tried to pass this instance to the onSomething function, that way i expose all plugin data and then i can do something like,
onSomething(instance){
instance.someMethod();
instance.init();
//or anything i want
}
To me me it looks quite wrong so there must be a better way... or not?

Well im not sure if it is the best idea, but you could pass the current object as a parameter. Let's say onSomething : function(obj) { }
So whenever "onSomething" is called by the plugin, you can call it like this: "onSomething(this)" and then refer to the object asobject`
Lets give a specific example.
var plugin = function (opts) {
this.onSomething = opts.onSomething;
this.staticProperty = 'HELLO WORLD';
this.init = function() {
//Whatever and lets pretend you want your callback right here.
this.onSomething(this);
}
}
var test = new Plugin({onSomething: function(object) { alert(object.staticProperty) });
test.init(); // Alerts HELLO WORLD
Hope this helps, tell me if its not clear enough.
Oh wait, thats what you did.

Related

How to redefine private method in javascript?

I create component from Trumbowyg plugin to vue.js library. I need add two way binding in this beautiful wysiwyg editor.
How to rewrite buildEditor() method?
This method is private. how to do it correctly?
<script>
jQuery.trumbowyg = {
// options object
};
(function (navigator, window, document, $, undefined) {
$.fn.trumbowyg = function (options, params) {
// ... code ...
$(this).data('trumbowyg', new Trumbowyg(this, options));
// ... code ...
};
var Trumbowyg = function (editorElem, o) {
var t = this;
// ... code ...
t.init();
};
Trumbowyg.prototype = {
init: function () {
var t = this;
t.buildEditor();
// ... code ...
},
buildEditor: function () {
// i need rewrite this method
}
// code for otner method
};
})(navigator, window, document, jQuery);
// -------------------------------------
// other file. I want init this plugin
// here do need to rewrite buildEditor() method? What best way to do this?
$('.selector').trumbowyg();
If this plugin doesn't return 'Trumbowyg' variable it's not possible. I recommend fork this plugin and create your own version with your settings.
The best way to do it would be to fork the plugin yourself, as Slava answered. But technically you're able to modify that function.
Whenever you construct a class, that instance has its own constructor property. This is equal to the class function.
So, if you can get access to an instance of Trumbowyg, you're able to use its class:
$foo.trumbowyg(...)
var trumbowyg = $foo.data('trumbowyg')
var TrumbowygClass = trumbowyg.constructor
Now we can modify its prototype:
TrumbowygClass.prototype.buildEditor = function() {
// ...
}
You might want to make $foo be a temporary or unused element. That's because it'll have called the old buildEditor (as soon as you ran $foo.trumbowyg()), not your own modified version.
After you've set the prototype function you could run it on the element you actually want to use trumbowyg on (e.g. $('#target'))
As an example:
(function() {
window.makeInstance = function() {
return new HiddenClass()
}
var HiddenClass = function() {
this.setGreeting()
this.showGreeting()
}
HiddenClass.prototype.setGreeting = function() {
this.greeting = 'Hello, world!'
}
HiddenClass.prototype.showGreeting = function() {
console.log(this.greeting)
}
})()
var myTempInstance = makeInstance()
// Should log 'Hello, world!'
var HiddenClass = myTempInstance.constructor
console.log(HiddenClass) // Should be the HiddenClass function
// Now we overwrite our function..
HiddenClass.prototype.setGreeting = function() {
this.greeting = 'Redefined!'
}
var myUsedInstance = makeInstance()
// Should log 'Redefined!', since we redefined setGreeting
// And later we can use `myUsedInstance`.
// In this code myTempInstance is like $foo, and myUsedInstance
// is like $('#target').

Properly get "this" in jQuery plugin member

I have a JavaScript module that I would like to create a jQuery plugin interface to.
The module itself is like this:
var Foo = (function () {
"use strict";
var self = {};
self.add = function (selector, otherParam)
{
// Does things unto selector.
// Precisely what it does doesn't matter.
};
return self;
}());
and is used, with success, like this:
Foo.add(a);
Now, I would like to create a plugin that interfaces to this module,
so I can use it somewhat like this:
$.fn.foo = Foo;
$.fn.foo.add = function (param) {
var selector = this;
Foo.add(selector, param);
}
$(elem).foo.add(a);
The problem I'm facing is that I can't get "this" working in .add().
The best way I managed to do it was to not have Foo be self-initializing,
and use a syntax like:
$.fn.foo = Foo;
$(elem).foo().add(a);
It works, but I find it less aesthatically pleasing and less "clean".
Is there a way to do this? Am I on the wrong approach altogether?
Thankful for any input, and I apologize in advance if this has already been answered or is unfit in any other way.
I did search for answers, but I'm not well-versed in plugin authoring nor an expert on jQuery itself.
TL;DR: I have a module like Foo above, and would like to access it's members like a jQuery plugin.
Here is a simplified version of the pattern I normally use (error checking and extra features removed).
It uses a single class function and a plugin bridge extension method to allow attachment to multiple elements. Methods are called by using a string option value:
var Foo = (function () {
"use strict";
// Constructor
function Foo($element, options){
this.$element = $element;
this.options = options
this.fooVal = 0;
}
// Create method (called from bridge)
Foo.prototype.onCreate = function(){
this.fooVal = ~~this.$element.text()
};
// Add the specified val to the elements current value
Foo.prototype.add = function (val) {
this.fooVal += val;
// Update the element text with the new value
this.$element.text(this.fooVal);
};
return Foo;
})();
// Create a bridge to each element that needs a Foo
$.fn.foo = function (options, args) {
this.each(function () {
var $element = $(this);
// Try to get existing foo instance
var foo = $element.data("Foo");
// If the argument is a string, assume we call that function by name
if (typeof options == "string") {
foo[options](args);
}
else if (!foo) {
// No instance. Create a new Foo and store the instance on the element
foo = new Foo($element, options);
$element.data("Foo", foo);
// Record the connected element on the Foo instance
foo.$element = $element;
// Call the initial create method
foo.onCreate();
}
});
}
// testing
console.clear();
$('#test').foo();
$('#button2').click(function () {
$('#test').foo("add", 2);
});
$('#button10').click(function () {
$('#test').foo("add", 10);
});
For your example Foo takes the initial value from the element text and subsequent "add" calls modify that value.
JSFiddle: http://jsfiddle.net/TrueBlueAussie/o2u7egfy/3/
Notes:
~~ is just a fast short-cut for parseInt()
You could supply an initial value via the options parameter (ignored in first example). See following:
e.g.
// Create method (called from bridge)
Foo.prototype.onCreate = function(){
this.fooVal = this.options.value || ~~this.$element.text()
// Set initial value
this.$element.text(this.fooVal);
};
and start with
$('#test').foo({value: 999});
JSFiddle: http://jsfiddle.net/TrueBlueAussie/o2u7egfy/4/

How to create a single jquery plugin function that is callable both on jQuery instances and the jQuery object itself?

I have created JQuery plugin like this:
$.fn.myPlugin = function(className)
{
if(className) {
// create new instance of className and return it
} else {
$(this).css("background-color","red");
}
};
When I use it like this: $("div").myPlugin(); it works fine.
Buy when I use $.myPlugin("TestClass") it does not work.
note: TestClass exist.
If you want $.customFunction to be set, you need to assign a value to it:
$.customFunction = function () {
alert('this works!');
};
given your update, you should use two separate functions:
$.myPlugin = function (classname) {
//create new instance of className and return it
}
$.fn.myPlugin = function () {
this.css('background-color', 'red');
};
Use the jQuery extend function:
jQuery.fn.extend({
myFunction: function(){
alert("Hi!");
}
});
Good luck!
For a simple plugin like that (that has no notion of this), you might want something like
$.myPlugin = $.fn.myPlugin = function()
{
alert("test");
};
$.fn is the prototype, so you're giving every jQuery instance that function (method, really).
Direct assignment to $ will make it a static function on the global jQuery object.
To update my answer to your updated question, here's one way to do what I think you want to do (keep it all in one function? -- please note: I am trying to read your mind here ;):
$.myPlugin = $.fn.myPlugin = function(className) {
var isInstance = (this instanceof $); // true if invoked on an instance
if (className) { // whenever a className is given
className = '.' + className; // turn it into a selector (assumes only one class)
return isInstance ? $(className, this) : $(className); // returns jQuery object
} else if (isInstance) { // when invoked on an instance
return this.css("background-color","red"); // sets color and returns this
}
};
If you want two completely different behaviors based on how the plugin is called, however, it is clearer and more maintainable to write them as two separate functions:
// returns jQuery object containing element(s) that have a given className
$.myPlugin = function(className) {
// turn className into selector (assumes only one class name is given)
var selector = className ? ('.' + className) : '';
return $(selector);
};
// sets color and returns this
$.fn.myOtherPlugin = function() {
return this.css('background-color', 'red');
};
You may additionally want to give the plugins different names that are indicative of their respective functions (hence myOtherPlugin).

Use jquery selector and events to call function in javascript object

ok I'm not sure if I'm doing this right so if I'm going about it all wrong please explain.
I have a javascript object which is drawing html based on ajax data.
I am then trying to use jquery to handle events on the html output from an instance of the above object. However I would like to call a function and get a property out of the instance of the javascript object which was used to draw the html.
so my code looks something like this:
function obj1 (){
this.property1 = "propvalue";
this.dosomething = function () {
// does some processing
}
this.drawhtml = function () {
// outputs html
}
}
// jquery to handle events
$(document).ready(function(){
// .edit is a class in the html outputted from the drawhtml
$('body').on('click','.edit',function () {
// call the dosomething from the object
});
});
// create instance of object could be multiple on on page
var instance1 = new obj1;
instance1.drawhtml();
Thanks,
You can just use the instance you created before:
// jquery to handle events
$(document).ready(function(){
// .edit is a class in the html outputted from the drawhtml
$('body').on('click','.edit',function () {
instance1.dosomething();
});
});
// create instance of object could be multiple on on page
var instance1 = new obj1(); // added parentesis so it's valid javascript
instance1.drawhtml();
EDIT: Additional information starting from the comments:
The best way to handle this is to tie your event handler to the object itself. Something like this:
function obj1 (){
this.property1 = "propvalue";
this.dosomething = function () {
// does some processing
}
this.drawhtml = function () {
var elem = $("<div>my super dooper HTML</div>");
elem.on('click', this.dosomething);
}
}

Javascript inheritance and method overriding

Assume I have a class like this:
function Widget() {
this.id = new Date().getTime();
// other fields
}
Widget.prototype = {
load: function(args) {
// do something
}
}
From this class I created some other classes which inherit the same prototype but have some added methods. What I want to do is being able to define a load() method in the sub-classes which first calls the parent method and then execute some code. Something like:
SpecialWidget.prototype = {
load: function(args) {
super.load(args);
// specific code here
}
}
I know there's no super keyword in Javascript but there must be a way to do this.
You can simulate it like this:
SpecialWidget.prototype = {
load: function(args) {
Widget.prototype.load.call(this, args);
// specific code here
}
}
Or you can create your own super property like this:
SpecialWidget.prototype.parent = Widget.prototype;
SpecialWidget.prototype = {
load: function(args) {
this.parent.load.call(this,args);
// specific code here
}
}
so first, you set up your 'subclass' like so
function SubClass(name) {
Super.call(this);
// stuff here
}
SubClass.prototype = new SuperClass(null);
SubClass.prototype.constructor = SubClass;
and then you can do
SuperClass.prototype.theMethod.apply(this);
from within a subclass implementation to specifically invoke the super's implementation.
I don't know if this is the best solution, but you could do something like this:
function Widget() {
this.id = new Date().getTime();
}
Widget.prototype.load = function(args) {
alert( 'parent load' );
};
SpecialWidget = function(){};
// Make the prototype of SpecialWidget an instance of Widget
var proto = SpecialWidget.prototype = new Widget;
// Give the prototype a function that references the "load" from Widget
proto.parent_load = proto.load;
// Give SpecialWidget its own "load" that first calls the parent_load
proto.load = function( args ) {
this.parent_load( args );
alert( 'special load' );
};
var inst = new SpecialWidget;
inst.load();
This makes the prototype of SpecialWidget an instance of Widget so that it inherits all that Widget has.
Then it makes a reference to the load() of Widget called parent_load(), and creates its own load() that calls the parent_load() when invoked.
Since mid-2015 (ECMAScript 2015), javascript has Classes and super
Here's the link: https://262.ecma-international.org/6.0/, see section 12.3.5 (super) and 14.5 (Class definitions).
How your code would look with those changes:
class Widget() {
constructor() {
this.id = new Date().getTime();
// other fields
}
load(args) {
// do something
}
}
class SpecialWidget extends Widget {
load(args) {
super.load(args);
// specific code here
}
}
The closest I got to the previous syntax (without using class but using super) was using Object.setPrototypeOf:
// UNCHANGED
function Widget() {
this.id = new Date().getTime();
// other fields
}
Widget.prototype = {
load: function(args) {
// do something
}
}
// slightly changed to declare SpecialWidget
function SpecialWidget() {}
// changed to define load as an method, and not a property with function as value
SpecialWidget.prototype = {
load(args) {
super.load(args);
// specific code here
}
}
// here's the key
Object.setPrototypeOf(SpecialWidget.prototype, Widget.prototype);
The declaration of load was changed because super can be used inside methods, but not functions. So, instead of load: function(args) { body }, it's simply load(args) { body }.
But, there's a caveat: with this solution, elements of SpecialWidget will not inherit the id defined as new Date().getTime(). I don't think there's a workahound (without using classes or duplicating code declaring this.id inside SpecialWidget).
It would be possible to store the old value of the load method in a closure, if you did your overriding like this:
function Widget() {
this.id = new Date().getTime();
// other fields
}
Widget.prototype = {
load: function(args) {
// do something
alert("Widget Prototype Load");
}
};
function SpecialWidget(){
};
SpecialWidget.prototype = new Widget();
(function(){
var oldLoad = SpecialWidget.prototype.load;
SpecialWidget.prototype.load = function(){
oldLoad();
alert("new Load");
};
}());
var x = new SpecialWidget();
x.load();
It works, but I'm not sure if it's the best method.
Using Simple Javascript Class:
Class.extend('Widget', {
load: function () {
alert('foo');
}
});
Widget.extend('SpecialWidget', {
load: function () {
this.super();
alert('bar');
}
});
new Widget().load(); // Alert: 'foo'
new SpecialWidget().load(); // Alert: 'foo' and 'bar'
Take a look at Simple Javascript Class Project, Simple JavaScript Inheritance and Inheritance Patterns in JavaScript.

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