We Keep Coding

Using bind function in event listeners

I have been writing a plugin, and i really like this format
Function.prototype._onClick = function() {
// do something
}
Fuction.prototype.addListner = function() {
this.$element.on('click', this._onClick.bind(this));
}
the problem is sometimes i need the element being clicked and the main object. Doing as below i loose the dom element and not using bind looses the main object.
Fuction.prototype.addListner {
this.$element.find('.some-class').on('click', this._onClick.bind(this));
}
To achieve that i go back to ugly version
Fuction.prototype.addListner = function() {
var self = this;
this.$element.find('.some-class').on('click', function() {
self._onClick($(this));
});
}
Is there any better way to do this?

As zerkms, you can use the event.target to achieve what you want.
When using .on, the handler is :
handler
Type: Function( Event eventObject [, Anything extraParameter ] [, ...
] ) A function to execute when the event is triggered. The value false
is also allowed as a shorthand for a function that simply does return
false.
So your _onClick function will receive click event as its 1st parameter, then from event.target, you can now get the clicked item.
var Test = function(sel) {
this.$element = $(sel);
this.value = 'My value is ' + this.$element.data('val');
};
Test.prototype.addListner = function() {
this.$element.find('.some-class').on('click', this._onClick.bind(this));
}
Test.prototype._onClick = function(evt) {
// Get the target which is being clicked.
var $taget = $(evt.target);
//
console.log(this.value);
// use $target to get the clicke item.
console.log($taget.data('val'));
}
var test = new Test('#test');
test.addListner();
<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.3/jquery.min.js"></script>
<div id="test" data-val="divVal">
<button class="some-class" data-val="Button-A">btnA</button>
<button class="some-class" data-val="Button-B">btnB</button>
</div>

How to achieve a queue of object instances of jQuery modals, assuring only one instance is on per time?

I've a task of building a modal prompt, that's been simple so far describing its methods like "show", "hide" when it comes down just to DOM manupulation.
Now comes the hardship for me... Imagine we have a page on which there are several immediate calls to construct and show several modals on one page
//on page load:
$("browser-deprecated-modal").modal();
$("change-your-city-modal").modal();
$("promotion-modal").modal();
By default my Modal (and other libraries i tried) construct all of these modals at once and show them overlapping each other in reverse order -
i.e $(promotion-modal) is on the top, while the
$("browser-deprecated-modal") will be below all of them. that's not what i want, let alone overlapping overlays.
I need each modal to show up only when the previous one (if there'are any) has been closed. So, first we should see "browser-deprecated-modal" (no other modals underneath), upon closing it there must pop up the second one and so on.
I've been trying to work it out with this:
$.fn.modal = function(options) {
return this.each(function() {
if (Modal.running) {
Modal.toInstantiateLater.push({this,options});
} else {
var md = new Modal(this, options);
}
});
}
destroy :function () {
....
if (Modal.toInstantiateLater.length)
new Modal (Modal.toInstantiateLater[0][0],Modal.toInstantiateLater[0][1]);
}
keeping a track of all calls to construct a Modal in a array and in the "destroy" method make a check of this array is not empty.
but it seems awkward and buggy me thinks.
i need a robust and clear solution. I've been thinking about $.Callbacks or $.Deferred,
kinda set up a Callback queue
if (Modal.running) { //if one Modal is already running
var cb = $.Callbacks();
cb.add(function(){
new Modal(this, options);
});
} else { //the road is clear
var md = new Modal(this, options);
}
and to trigger firing cb in the destroy method, but i'm new to this stuff and stuck and cannot progress, whether it's right or not, or other approach is more suitable.
Besides, I read that callbacks fire all the functions at once (if we had more than one extra modal in a queue), which is not right, because I need to fire Modal creation one by one and clear the Callback queue one by one.
Please help me in this mess.
My code jsfiddle

I got rid of the counter variable, as you can use toInstantiateLater to keep track of where you are, and only had to make a few changes. Give this a try...
Javscript
function Modal(el, opts){
this.el = $(el);
this.opts = opts;
this.overlay = $("<div class='overlay' id='overlay"+Modal.counter+"'></div>");
this.wrap = $("<div class='wrap' id='wrap"+Modal.counter+"'></div>");
this.replace = $("<div class='replace' id='replace"+Modal.counter+"'></div>");
this.close = $("<span class='close' id='close"+Modal.counter+"'></span>")
if (Modal.running) {
Modal.toInstantiateLater.push(this);
}
else {
Modal.running = true;
this.show();
}
}
Modal.destroyAll = function() {
Modal.prototype.destroyAll();
};
Modal.prototype = {
show: function() {
var s = this;
s.wrap.append(s.close);
s.el.before(s.replace).appendTo(s.wrap).show();
$('body').append(s.overlay).append(s.wrap);
s.bindEvents();
Modal.currentModal = s;
},
bindEvents: function() {
var s = this;
s.close.on("click.modal",function(e){
s.destroy.call(s,e);
});
},
destroy: function(e) {
var s = this;
s.replace.replaceWith(s.el.hide());
s.wrap.remove();
s.overlay.remove();
if (Modal.toInstantiateLater.length > 0) {
Modal.toInstantiateLater.shift().show();
}
else {
Modal.running = false;
}
},
destroyAll: function(e) {
Modal.toInstantiateLater = [];
Modal.currentModal.destroy();
}
}
Modal.running = false;
Modal.toInstantiateLater = [];
Modal.currentModal = {};
$.fn.modal = function(options) {
return this.each(function() {
var md = new Modal(this, options);
});
}
$("document").ready(function(){
$("#browser-deprecated-modal").modal();
$("#change-your-city-modal").modal();
$("#promotion-modal").modal();
$("#destroy-all").on("click", function() {
Modal.destroyAll();
});
});
jsfiddle example
http://jsfiddle.net/zz9ccbLn/4/

Multiple instances of a JavaScript carousel

So I have the following code I have written to build a carousel in JavaScript using Hammer.js and jQuery:
var hCarousel = {
container: false,
panes: false,
pane_width: 0,
pane_count: 0,
current_pane: 0,
build: function( element ) {
hCarousel.container = $(element).find('.hcarousel-inner-container');
hCarousel.panes = $(hCarousel.container).find('> .section');
hCarousel.pane_width = 0;
hCarousel.pane_count = hCarousel.panes.length;
hCarousel.current_pane = 0;
hCarousel.setPaneDimensions( element );
$(window).on('load resize orientationchange', function() {
hCarousel.setPaneDimensions( element );
});
$(element).hammer({ drag_lock_to_axis: true })
.on('release dragleft dragright swipeleft swiperight', hCarousel.handleHammer);
},
setPaneDimensions: function( element ){
hCarousel.pane_width = $(element).width();
hCarousel.panes.each(function() {
$(this).width(hCarousel.pane_width);
});
hCarousel.container.width(hCarousel.pane_width*hCarousel.pane_count);
},
next: function() {
return hCarousel.showPane(hCarousel.current_pane+1, true);
},
prev: function() {
return hCarousel.showPane(hCarousel.current_pane-1, true);
},
showPane: function( index ) {
// between the bounds
index = Math.max(0, Math.min(index, hCarousel.pane_count-1));
hCarousel.current_pane = index;
var offset = -((100/hCarousel.pane_count)*hCarousel.current_pane);
hCarousel.setContainerOffset(offset, true);
},
setContainerOffset: function( percent, animate ) {
hCarousel.container.removeClass("animate");
if(animate) {
hCarousel.container.addClass("animate");
}
if(Modernizr.csstransforms3d) {
hCarousel.container.css("transform", "translate3d("+ percent +"%,0,0) scale3d(1,1,1)");
}
else if(Modernizr.csstransforms) {
hCarousel.container.css("transform", "translate("+ percent +"%,0)");
}
else {
var px = ((hCarousel.pane_width*hCarousel.pane_count) / 100) * percent;
hCarousel.container.css("left", px+"px");
}
},
handleHammer: function( ev ) {
ev.gesture.preventDefault();
switch(ev.type) {
case 'dragright':
case 'dragleft':
// stick to the finger
var pane_offset = -(100/hCarousel.pane_count)*hCarousel.current_pane;
var drag_offset = ((100/hCarousel.pane_width)*ev.gesture.deltaX) / hCarousel.pane_count;
// slow down at the first and last pane
if((hCarousel.current_pane == 0 && ev.gesture.direction == Hammer.DIRECTION_RIGHT) ||
(hCarousel.current_pane == hCarousel.pane_count-1 && ev.gesture.direction == Hammer.DIRECTION_LEFT)) {
drag_offset *= .4;
}
hCarousel.setContainerOffset(drag_offset + pane_offset);
break;
case 'swipeleft':
hCarousel.next();
ev.gesture.stopDetect();
break;
case 'swiperight':
hCarousel.prev();
ev.gesture.stopDetect();
break;
case 'release':
// more then 50% moved, navigate
if(Math.abs(ev.gesture.deltaX) > hCarousel.pane_width/2) {
if(ev.gesture.direction == 'right') {
hCarousel.prev();
} else {
hCarousel.next();
}
}
else {
hCarousel.showPane(hCarousel.current_pane, true);
}
break;
}
}
}
And I call this like:
var hSections;
$(document).ready(function(){
hSections = hCarousel.build('.hcarousel-container');
});
Which works fine. But I want to make it so that I can have multiple carousels on the page which again works... but the overall width of the container is incorrect because it's combining the width of both carousels.
How can I run multiple instances of something like this, but the code know WHICH instance it's interacting with so things don't become mixed up, etc.

The problem is your design is not really suited to multiple instances, because of the object literal which has properties of the carousel, but also the build method.
If I was starting this from scratch, I would prefer a more OOP design, with a carousel class that can you instantiate, or have it as a jQuery plugin. That said, it's not impossible to adapt your existing code.
function hCarousel(selector){
function hCarouselInstance(element){
var hCarousel = {
// insert whole hCarousel object code
container: false,
panes: false,
build : function( element ){
...
};
this.hCarousel = hCarousel;
hCarousel.build(element);
}
var instances = [];
$(selector).each(function(){
instances.push(new hCarouselInstance(this));
});
return instances;
}
Usage
For example, all elements with the hcarousel-container class will become an independant carousel.
$(document).ready(function(){
var instances = hCarousel('.hcarousel-container');
});
Explanation:
The hCarousel function is called passing the selector, which can match multiple elements. It could also be called multiple times if needed.
The inner hCarouselInstance is to be used like a class, and instantiated using the new keyword. When hCarousel is called, it iterates over the matched elements and creates a new instance of hCarouselInstance.
Now, hCarouselInstance is a self contained function that houses your original hCarousel object, and after creating the object it calls hCarousel.build().
The instances return value is an array containing each instance object. You can access the hCarousel properties and methods from there, such as:
instances[0].hCarousel.panes;
jQuery plugin
Below is a conversion to a jQuery plugin, which will work for multiple carousels.
(function ( $ ) {
$.fn.hCarousel = function( ) {
return this.each(function( ) {
var hCarousel = {
// insert whole hCarousel object code here - same as in the question
};
hCarousel.build(this);
});
};
}( jQuery ));
Plugin usage:
$('.hcarousel-container').hCarousel();

I would try turning it into a function which you can use like a class. Then you can create separate objects for your carousels.
So you would have something like the following:
function HCarousel (element) {
this.element=element;
this.container= false;
this.panes= false;
this.pane_width= 0;
this.pane_count= 0;
this.current_pane= 0;
}
And then add each method on the class like this.
HCarousel.prototype.build = function() {
this.container = $(element).find('.hcarousel-inner-container');
this.panes = $(hCarousel.container).find('> .section');
this.pane_width = 0;
this.pane_count = hCarousel.panes.length;
this.current_pane = 0;
this.setPaneDimensions( element );
$(window).on('load resize orientationchange', function() {
this.setPaneDimensions( element );
});
$(this.element).hammer({ drag_lock_to_axis: true }).on('release dragleft dragright swipeleft swiperight', hCarousel.handleHammer);
};
etc. That should give you the basic idea. Will take a little bit of re-writing, but then you can create a carousel with something like this:
var carousel1 = new HCarousel('.hcarousel-container');
Hope that puts you on the right track.
Classes don't actually exist in JS, but this is a way to simulate one using a function. Here's a good article on using classes in JS http://www.phpied.com/3-ways-to-define-a-javascript-class/

jQuery plugin method to get object properties

I´m building a jQuery extension plugin with the following standard:
(function ($) {
var version = "1.1.0";
var active = false;
$.fn.inputPicker = function (options) {
return this.each(function () {
if ($(this)[0].tagName !== 'DIV')
throw new ReferenceError('mz.ui.dialog.dateTimePicker: Method works only on DIV types.');
/// Label
var labelObj = $("<label class='small'>Data Hora Inicial</label>");
$(this).append(labelObj);
/// Input
var inputObj = $("<input type='datetime-local' class='form-control input-sm'></input>");
$(this).append(inputObj);
})
});
};
}(jQuery));
And here is how I call it:
<div id='test'></div>
$('#test').inputPicker();
Later in code I wanna get the data that was entered in the input field, something like:
$('test').inputPicker().getInputData();
What´s the best way to accomplish that ? I´ve tried something like:
this.getInputData = function () {
return $(inputObj).val();
}
But got errors when calling the function.
Can someone help me with this ? Thanks in advance...

You could just make another method to get the input data like this using the DOM structure and class names that you added:
$.fn.getInputData = function() {
return this.eq(0).find("input.input-sm").val();
}
This would operate only on the first DOM element in the jQuery object (since it's returning only a single value).
So, after setting it up like you did:
$("#test").inputPicker();
You'd then retrieve the data like this:
var data = $("#test").getInputData();

Most elegant way to have one HTML element mirror another?

If I have two HTML elements that should always contain the same inner HTML text, what is the most elegant way to update them both at the same time?
For example:
<head>
<title id="pageTitle">My Application</title>
</head>
<body>
<h1 id="screenTitle">My Application</h1>
</body>
I would like the innerHTML of screenTitle and pageTitle to remain identical whenever a JavaScript function changes one of them.
I know I can iterate through the pageTitle and screenTitle elements, updating each of them whenever I change the string "My Application", but is there a more elegant way?

document.title.innerHTML is read-only in IE. This supposed to be a cross-browser method:
document.getElementById('screenTitle').innerHTML = document.title = 'My Application';
Instead of a literal value you can use a variable ofcourse.
If you really need something "elegant" (=== exotic), you can use a setter:
var page = {
set title(text) {
document.getElementById('screenTitle').innerHTML = document.title = text;
}
};
When ever you need to change the titles, just set it: page.title = newTitle;. Only you need to care of, is that you can refer page object from the current scope. Also this will only work in modern browsers.

Use a single function that encapsulates writes to both elements. So instead of directly using DOM methods, the rest of your code would use a function such as:
function setTitle(newTitle)
{
document.getElementById('pageTitle').innerHTML = newTitle;
document.getElementById('screenTitle').innerHTML = newTitle;
}
Of course this could be optimized/DRYed/refactored/overengineered ad nauseam...
function setTitle(newTitle)
{
if (setTitle.elements)
{
var id = document.getElementByIdl
setTitle.elements = [id('pageTitle'), id('screenTitle')];
}
setTitle.elements.forEach(function (elt)
{
elt.innerHTML = newTitle;
});
}

You should make a JS method that updates both simultaneously as long as you are in control of all the code that is going to modify the elements. Something like:
function updateElementGroup( newInnerHTML ) {
document.getElementById( 'pageTitle' ).innerHTML = newInnerHTML;
document.getElementById( 'screenTitle' ).innerHTML = newInnerHTM;
}
Which you can use like this:
updateElementGroup( 'New Text' );
If you are not in control of all the code you could set up some listeners to catch whenever one is changed and update the other one accordingly, something like this:
var isUpdating = false;
var elements = [
document.getElementById( 'pageTitle' ),
document.getElementById( 'screenTitle' ),
];
for ( i in elements ) {
elements[i].addEventListener( 'DOMCharacterDataModified', function( evt ) {
if ( isUpdating ) {
return;
}
isUpdating = true;
for ( i in elements ) {
elements[i].innerHTML = evt.newValue;
}
isUpdating = false;
} );
}

Using jQuery:
$('#pageTitle').bind('DOMSubtreeModified', function() {
if ($('#pageTitle').html() != $('#screenTitle').html())
$('#screenTitle').html($('#pageTitle').html());
});
$('#screenTitle').bind('DOMSubtreeModified', function() {
if ($('#pageTitle').html() != $('#screenTitle').html())
$('#pageTitle').html($('#screenTitle').html());
});