Develop Reference

jQuery plugin instances variable with event handlers

I am writing my first jQuery plugin which is a tree browser. It shall first show the top level elements and on click go deeper and show (depending on level) the children in a different way.
I got this up and running already. But now I want to implement a "back" functionality and for this I need to store an array of clicked elements for each instance of the tree browser (if multiple are on the page).
I know that I can put instance private variables with "this." in the plugin.
But if I assign an event handler of the onClick on a topic, how do I get this instance private variable? $(this) is referencing the clicked element at this moment.
Could please anyone give me an advise or a link to a tutorial how to get this done?
I only found tutorial for instance specific variables without event handlers involved.
Any help is appreciated.
Thanks in advance.
UPDATE: I cleaned out the huge code generation and kept the logical structure. This is my code:
(function ($) {
$.fn.myTreeBrowser = function (options) {
clickedElements = [];
var defaults = {
textColor: "#000",
backgroundColor: "#fff",
fontSize: "1em",
titleAttribute: "Title",
idAttribute: "Id",
parentIdAttribute: "ParentId",
levelAttribute: "Level",
treeData: {}
};
var opts = $.extend({}, $.fn.myTreeBrowser.defaults, options);
function getTreeData(id) {
if (opts.data) {
$.ajax(opts.data, { async: false, data: { Id: id } }).success(function (resultdata) {
opts.treeData = resultdata;
});
}
}
function onClick() {
var id = $(this).attr('data-id');
var parentContainer = getParentContainer($(this));
handleOnClick(parentContainer, id);
}
function handleOnClick(parentContainer, id) {
if (opts.onTopicClicked) {
opts.onTopicClicked(id);
}
clickedElements.push(id);
if (id) {
var clickedElement = $.grep(opts.treeData, function (n, i) { return n[opts.idAttribute] === id })[0];
switch (clickedElement[opts.levelAttribute]) {
case 1:
renderLevel2(parentContainer, clickedElement);
break;
case 3:
renderLevel3(parentContainer, clickedElement);
break;
default:
debug('invalid level element clicked');
}
} else {
renderTopLevel(parentContainer);
}
}
function getParentContainer(elem) {
return $(elem).parents('div.myBrowserContainer').parents()[0];
}
function onBackButtonClick() {
clickedElements.pop(); // remove actual element to get the one before
var lastClickedId = clickedElements.pop();
var parentContainer = getParentContainer($(this));
handleOnClick(parentContainer, lastClickedId);
}
function renderLevel2(parentContainer, selectedElement) {
$(parentContainer).html('');
var browsercontainer = $('<div>').addClass('myBrowserContainer').appendTo(parentContainer);
//... rendering the div ...
// for example like this with a onClick handler
var div = $('<div>').attr('data-id', element[opts.idAttribute]).addClass('fct-bs-col-md-4 pexSubtopic').on('click', onClick).appendTo(subtopicList);
// ... rendering the tree
var backButton = $('<button>').addClass('btn btn-default').text('Back').appendTo(browsercontainer);
backButton.on('click', onBackButtonClick);
}
function renderLevel3(parentContainer, selectedElement) {
$(parentContainer).html('');
var browsercontainer = $('<div>').addClass('myBrowserContainer').appendTo(parentContainer);
//... rendering the div ...
// for example like this with a onClick handler
var div = $('<div>').attr('data-id', element[opts.idAttribute]).addClass('fct-bs-col-md-4 pexSubtopic').on('click', onClick).appendTo(subtopicList);
// ... rendering the tree
var backButton = $('<button>').addClass('btn btn-default').text('Back').appendTo(browsercontainer);
backButton.on('click', onBackButtonClick);
}
function renderTopLevel(parentContainer) {
parentContainer.html('');
var browsercontainer = $('<div>').addClass('fct-page-pa fct-bs-container-fluid pexPAs myBrowserContainer').appendTo(parentContainer);
// rendering the top level display
}
getTreeData();
//top level rendering! Lower levels are rendered in event handlers.
$(this).each(function () {
renderTopLevel($(this));
});
return this;
};
// Private function for debugging.
function debug(debugText) {
if (window.console && window.console.log) {
window.console.log(debugText);
}
};
}(jQuery));

Just use one more class variable and pass this to it. Usually I call it self. So var self = this; in constructor of your plugin Class and you are good to go.
Object oriented way:
function YourPlugin(){
var self = this;
}
YourPlugin.prototype = {
constructor: YourPlugin,
clickHandler: function(){
// here the self works
}
}
Check this Fiddle
Or simple way of passing data to eventHandler:
$( "#foo" ).bind( "click", {
self: this
}, function( event ) {
alert( event.data.self);
});

You could use the jQuery proxy function:
$(yourElement).bind("click", $.proxy(this.yourFunction, this));
You can then use this in yourFunction as the this in your plugin.

disable function using javascript

I can not seem to find the code to disable a javascript function. What I want to do is have a javascript function and then I want to disable it. Here is the code:
<script>
var fooFunc = function fooFunction() {
alert("HELLO");
};
$(document).ready(function() {
fooFunc.disable();
});
</script>
<button onclick="fooFunc()">Button</button>
Basically, when the button is click the function should not work, it should be disabled. Thanks

"Disabling" fooFunc is the same as setting it to an empty function (not to null--that will cause an error when it is called the next time). In this case:
$(document).ready(function() {
fooFunc = function() { };
});
But I don't see how this is different from simply removing the onclick handler from the HTML element.
If you want the ability to disable/re-enable the function, you can write it like this:
fooFunc = function() {
function _fooFunc() {
if (!enabled) return;
alert("HELLO");
}
var enabled = true;
_fooFunc.enable = function() { enabled = true; };
_fooFunc.disable = function() { enabled = false; };
return _fooFunc;
}();
If you want to extend this to allow any function to be enabled/disabled, you can write a higher-order function, which takes any function as a parameter, and returns a function with enable and disable methods attached to it:
function disablable(fn) {
function inner() {
if (!enabled) return;
fn();
}
var enabled = true;
inner.enable = function() { enabled = true; };
inner.disable = function() { enabled = false; };
return inner;
}
Now you can define fooFunc as
var fooFunc = disablable(function fooFunction() {
alert("HELLO");
});
and the rest of your code will work as you want.

You can access the onclick property of the element..
<button id="id" onclick="fooFunc()">Button</button>
<script>
document.querySelector('#id').onclick = '';
</script>

If you don't want the function to work at all and be totally disabled then use the below.
If you want the function to work only under certain conditions then you will need if/else statements so it will work only when the conditions that you have set are met.
$(document).ready(function(){
$("button").onclick(function(event){
event.preventDefault();
});
});

You were going to define it back to undefined or null.
fooFunc=undefined;

You Should be doing this :) Change function definition on very first run and you are good to go.
<! DOCTYPE html>
<html lang="en">
<body>
<script>
var fooFunc = function() {
alert("HELLO");
fooFunc = function(){};
};
var enablefooFunc = function()
{
fooFunc = function() {
alert("HELLO");
fooFunc = function(){};
};
}
</script>
<button onclick="fooFunc()">Run once and Disable FooFunc</button>
<button onclick="enablefooFunc()">Enable FooFunc</button>
</body>
</html>

Understanding module design patterns in javascript

I am trying to understand module patterns in Javascript so that i can separate my code into different modules and use them where required.
var messageHandler = (function(){
var el;
var display = function(a){
if(a=='error'){
el = $('.error');
el.css('display','block');
}
else if (a==='success'){
el = $('.success');
el.css('display','block');
}
else if (a=='warning'){
el = $('.warning');
el.css('display','block');
}
else if (a=='danger'){
el = $('.danger');
el.css('display','block');
}
registerClick(el.find('.close'));
return this;
}
function registerClick(p_el){
p_el.bind('click',function(){
hide();
});
}
var hide = function(){
el.css('display','none');
}
return {
display: display,
hide: hide
}
})();
window.messageHandler = messageHandler;
messageHandler.display('warning');
So, I have four different classes in css for different types of messages.The close class is for a small cross button on the top right to close the message.
This works fine till i call the function only once.When i do this
messageHandler.display('warning');
messageHandler.display('success');
Now both the messages close button have been bind to the success close button because el gets overwritten.
How to achieve it keeping the code reusable and concise.

The problem here is that you have a closure variable el that you are overwriting every time display() is called. The hide() function uses whatever is the current value of el at the time it is called, so overwriting el is a problem.
If you want to have "static" functionality like this display() method, you need to avoid shared state.
As #Bergi points out in the comments, you can eliminate the shared el and modify hide() to take an element as input:
var messageHandler = (function(){
var el; // delete this
var display = function(a){
var el; // add this
function registerClick(el){
el.bind('click', function(){
hide(p_el);
});
}
function hide(el){
el.css('display','none');
}
You could also modify hide to make use of the current event properties, and then just have:
function registerClick(el){
el.bind('click', hide);
}
function hide(event){
$(event.target).css('display','none');
}
Cleaned up version including the auto-hide discussed in the comments:
var messageHandler = (function(){
var display = function(a){
var el = $('.' + a);
el.css('display', 'block');
var hideAction = function () { el.css('display', 'block'); };
var token = setTimeout(hideAction, 5000);
el.find('.close').bind('click', function () {
hideAction();
clearTimeout(token);
});
return this;
}
return {
display: display
}
})();

Multiple click handlers for a single element

I've written a few events to handle opening and closing of a snap js drawer. This code below works, but I feel it could be written more efficiently. Any suggestions?
function openMobileMenu() {
event.preventDefault();
snapper.open('left');
$('#btn-menu').off('click', openMobileMenu);
$('#btn-menu').on('click', closeMobileMenu);
}
function closeMobileMenu() {
event.preventDefault();
snapper.close('left');
$('#btn-menu').on('click', openMobileMenu);
$('#btn-menu').off('click', closeMobileMenu);
}
$('#btn-menu').on('click', openMobileMenu);

Make your code modular and your concepts explicit.
You can start by creating a MobileMenu object which encapsulates the logic.
Note: The following code was not tested.
var MobileMenu = {
_snapper: null,
_$button: null,
_direction: 'left',
init: function (button, snapper, direction) {
this._$button = $(button);
this._snapper = snapper;
if (direction) this._direction = direction;
this._toggleSnapperVisibilityWhenButtonClicked();
},
_toggleSnapperVisibilityWhenbuttonClicked: function () {
this._$button.click($.proxy(this.toggle, this));
},
toggle: function () {
var snapperClosed = this._snapper.state().state == 'closed',
operation = snapperClosed? 'open' : 'closed';
this._snapper[operation](this._direction);
}
};
Then in your page you can just do the following to initialize your feature:
var mobileMenu = Object.create(MobileMenu).init('#btn-menu', snapper);
Modularizing your code will make it more maintainable and understandable in the long run, but also allow you to unit test it. You also gain a lot more flexibily because of the exposed API of your component which allows other code to interact with it.
E.g. you can now toggle the menu visibility with mobileMenu.toggle().

Use a variable to keep track of the state:
var menu_open = false;
$("#btn-menu").on('click', function(event) {
event.preventDefault();
if (menu_open) {
snapper.close('left');
} else {
snapper.open('left');
}
menu_open = !menu_open; // toggle variable
});

snap has a .state() method, which returns an object stuffed with properties, one of which is .state.
I think you want :
$('#btn-menu').on('click', function() {
if(snapper.state().state == "closed") {
snapper.open('left');
} else {
snapper.close('left');
}
});
Or, in one line :
$('#btn-menu').on('click', function() {
snapper[['close','open'][+(snapper.state().state == 'closed')]]('left');
});
Also, check How do I make a toggle button? in the documentation.

JQuery prototype not working when traversing

I am using the following (http://jsfiddle.net/mkmurray/drv5w/27/) code to allow me to override the .show() function of a DIV.
<script>
(function ($) {
var _oldShow = $.fn.show;
$.fn.show = function (/*speed, easing, callback*/) {
var argsArray = Array.prototype.slice.call(arguments),
duration = argsArray[0],
easing,
callback,
callbackArgIndex;
// jQuery recursively calls show sometimes; we shouldn't
// handle such situations. Pass it to original show method.
if (!this.selector) {
_oldShow.apply(this, argsArray);
return this;
}
if (argsArray.length === 2) {
if ($.isFunction(argsArray[1])) {
callback = argsArray[1];
callbackArgIndex = 1;
} else {
easing = argsArray[1];
}
} else if (argsArray.length === 3) {
easing = argsArray[1];
callback = argsArray[2];
callbackArgIndex = 2;
}
return $(this).each(function () {
var obj = $(this),
oldCallback = callback,
newCallback = function () {
if ($.isFunction(oldCallback)) {
oldCallback.apply(obj);
}
obj.trigger('afterShow');
};
if (callback) {
argsArray[callbackArgIndex] = newCallback;
} else {
argsArray.push(newCallback);
}
obj.trigger('beforeShow');
_oldShow.apply(obj, argsArray);
});
};
})(jQuery);
</script>
I have the following HTML code
<div id="divBeforeHiddenDiv">
foo
</div>
<div id="hiddenDiv" style="display:none">
bar
</div>
And then:
<script>
$('#hiddendiv').bind("beforeShow", function () {
alert("show event successfully overridden");
});
</script>
It works great when I call $('#hiddenDiv').show() but not if I call $('#divBeforeHiddenDiv').next().show() the hidden div containing 'bar' shows but the alert is not displayed.
So why?
UPDATE
This appears to be a jQuery issue as per Bergi's comment. If I use this JSFiddle on jQuery 1.7.1 it works but using jQuery 1.10.1 or any higher version it does not: JSFiddle. Is there a better solution than simply downgrading?

You need to bind the events to the proper elements.
From the example you've given, and what I've interpreted, this piece of code
$('#beforeShow').bind("beforeShow", function () {
alert("show event successfully overridden");
});
Should be
$('#hiddenDiv').bind("beforeShow", function () {
alert("show event successfully overridden");
});
As you want the events to be bound to the hidden div. (or as described in the question, the div right after "#divBeforeHiddenDiv"
You also should change this piece
$('divBeforeHiddenDiv').next().show()
to this
$('#divBeforeHiddenDiv').next().show()
divBeforeHiddenDiv is an ID and in the first code snippet there is no id in the jQuery object.
JSFiddle