Recently, I'm coding javascript with little knowledge of it.
And here's my first javascript code which written this morning.
$(window).load(function(){
SubMenuHandler.init();
});
var SubMenuHandler = {
init : function() {
$("#statisticManager, #deviceManager, #policyManager").click(
function(event) {
var url = SubMenuHandler.getUrlFromEvent(event); // <-- These two
SubMenuHandler.redirectPage(url); // <-- lines
}
);
},
redirectPage : function(url) {
$(location).attr("href", url);
},
getUrlFromEvent : function(event) {
var target = event.target;
var url = $(target).data("url");
return url;
}
}
As you can see, SubMenuHandler is called recursively in the class.
But, I don't see how this is done as good. From my experiences with other languages, they usually use the this keyword instead of using the full name of class, except when accessing static variables.
Is there similar or better way to do this job?
init : function() {
var me = this; // <----- this is the magic
$("#statisticManager, #deviceManager, #policyManager").click(
function(event) {
var url = me.getUrlFromEvent(event);
me.redirectPage(url);
}
);
},
It is called "closures"
The random link from google: http://www.javascriptkit.com/javatutors/closures.shtml
And perfect answer here on SO: https://stackoverflow.com/a/111200/251311
Related
Can you use JQuery on a window reference? I have tried the following with no luck.
function GetDiPSWindow() {
var DiPSURL = "/DiPS/index";
var DiPSWindow = window.open("", "DiPS", "toolbar=no,location=no,status=no,menubar=no,scrollbars=yes,resizable=no,width=520,height=875");
if (DiPSWindow.location.href === "about:blank") {
DiPSWindow.location = DiPSURL;
}
return DiPSWindow;
}
function AddRecipient(field, nameId) {
// Get window
var win = GetDiPSWindow();
// Attempt 1
$(win.document).ready(function () {
var input = win.document.getElementById(field + "_Input");
input.value = nameId;
});
// Attempt 2
$(win).ready(function () {
var input = win.document.getElementById(field + "_Input");
input.value = nameId;
});
// Attempt 3
$(win).load(function () {
var input = win.document.getElementById(field + "_Input");
input.value = nameId;
});
}
Am I making a simple mistake?
EDIT For some reason, win.document.readyState is "complete". Not sure if that makes a difference.
I have also tried:
View contains:
<script>var CallbackFunction = function() {}; // Placeholder</script>
The method:
function AddRecipient(field, nameId) {
var DiPSURL = "/DiPS/index";
if (deliveryChannel === undefined) {
deliveryChannel = 0;
}
var DiPSWindow = GetDiPSWindow();
if (DiPSWindow.location.href === "about:blank") {
DiPSWindow.location = DiPSURL;
DiPSWindow.onload = function () { DiPSWindow.CallbackFunction = AddRecipient(field, nameId) }
} else {
var input = DiPSWindow.document.getElementById(field + "_Input");
input.value = input.value + nameId;
var event = new Event('change');
input.dispatchEvent(event);
}
}
The answer is.... kinda. it depends on what you are doing.
You can use jquery on the parent page to interact with a page within an iframe, however, anything that requires working with the iframe's document object may not work properly because jQuery keeps a reference of the document it was included on and uses it in various places, including when using document ready handlers. So, you can't bind to the document ready handler of the iframe, however you can bind other event handlers, and you can listen for the iframe's load event to know when it is absolutely safe to interact with it's document.
It would be easier though to just include jquery within the iframe itself and use it instead. It should be cached anyway, so there's no real detriment to performance by doing so.
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.
Is there a way to use jQuery selectors in modular way:
var logo = $('.logo', function() {
function show () {
console.log('logo has appeared');
$(this).addClass('logo-animated');
};
function hide() {
console.log('logo has been removed');
};
});
I want to be able to assign selector to variable and have some functions within it that I could be able access from outer it's scope.
NOTICE, that is pseudo code, I just drew you a picture of how I see it.
var selector = $('.someclass',
# here goes functions that I could access from outside;
);
UPDATE
var parallax = function() {
var images = ["http://localhost:8000/static/assets/images/hero-image-welcome.jpeg"];
var selector = $('.parallax-module');
var reload = function() {
console.log('reload')
};
$(selector).each(function(index) {
var image = {};
image.element = $(this);
image.height = image.element.height();
images.push(image);
$(this).css('background-image', 'url(' + images[index] + ')');
});
return {
images: images,
reload: reload()
}
}();
parallax.reload;
console.log(parallax.images[0])
// This goes without error, but isn't right;
var sParallax = $('.parallax-module');
sParallax.addClass('someClass');
// This would cause error;
parallax.addClass('someClass');
In this case I can use parallax public properties and methods, but I can't use selector (as I did in the beginning) without creating a new link to it. I know I can use public properties to access selector, but it's not the way I looking for.
You can just set the variable with your desired selector and then just add functions to that variable
var logo = $('.logo');
logo.show = function () {
console.log('logo has appeared');
$(this).addClass('logo-animated');
}
logo.hide = function () {
console.log('logo has been removed');
}
logo.show();
logo.hide();
JSFIDDLE
You can access through this:
logo.prevObject[0].show()//or hide()
I think I found the way, but it does not look right to me, it is working thought:
var parallax = function() {
var images = ["http://localhost:8000/static/assets/images/hero-image-welcome.jpeg"];
var selector = $('.parallax-module');
var reload = function() {
console.log('reload')
};
$(selector).each(function(index) {
var image = {};
image.element = $(this);
image.height = image.element.height();
images.push(image);
$(this).css('background-image', 'url(' + images[index] + ')');
});
return {
images: images,
reload: reload()
}
}().selector;
With selector reference in the end it is now valid to use parallax variable as simple link to DOM element, as well as to access functions that within it.
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
}
})();
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.