Reload/Re-Find Jquery Element - javascript

To demonstrate my issue, here I have small demo Script:
/user.html =
<div id="user-box"></div>
js =
class UserComponent {
constructor({}) {
this.srcFile = "/user.html";
this.parentBox = $("#container-box");
this.childBox = $("#user-box");
};
show(){
this.parentBox.load(this.srcFile, function() {
this.childBox.html("<p>Hello</p>")
}.bind(this));
};
}
The problem is that this line does not work correctly:
this.childBox.html("<p>Hello</p>")
For me the problem seems to be that when this.chilBox is referenced in the constructor, it does not yet exist in the DOM.
When I rewrite my code to:
this.parentBox.load(this.srcFile, function() {
var childBox = $("#user-box");
childBox.html("<p>Hello</p>")
}.bind(this));
Then it works. But I would like to reference the element in the constructor.
How can I reference the element in the constructor and then use it later when it exists?
I tried this.childBox.find().html("<p>Hello</p>") but like this it did not work.
Thanks for your help!

try this
this.childBox.html($("<p>Hello</p>"))
instead of
this.childBox.html("<p>Hello</p>")

Related

How to bind a method to `this` inside a constructor of a class (ES6)?

So I have the following simple ES6 plugin that can be used to change the background of an element (created for demo purpose) :
src/index.js
class changeBGColor {
constructor({ targetBG , triggerEl }) {
this.changeBGElem = document.getElementById(targetBG);
this.triggerElem = document.getElementById(triggerEl);
this.addEventListeners();
//this.onClick = this.onClick.bind(this);
//this.onClick.bind(this);
}
addEventListeners() {
this.triggerElem.addEventListener( 'click' , this.onClick.bind(this) );
}
changeBG() {
const bgChangeBgElem = this.changeBGElem;
bgChangeBgElem.classList.toggle('myclassName');
}
onClick(ev) {
console.log(this);
if( ev.target.hasAttribute('data-changeBG') ) {
this.changeBG();
}
}
}
export default changeBGColor;
And I am using my plugin in my main.js file like so:
src/main.js
import changeBGColor from './index.js';
new changeBGColor({
targetBG : 'changeBGOne',
triggerEl : 'triggerBGOne'
});
new changeBGColor({
targetBG : 'changeBGTwo',
triggerEl : 'triggerBGTwo'
});
Now the problem i have is inside addEventListeners method, I have the following code:
this.triggerElem.addEventListener( 'click' , this.onClick.bind(this) );
As you can see I use bind() to bind the scope of this to the class changeBGColor , but I don't want to do this in this manner.
I want something like:
this.onClick = this.onClick.bind(this); // i don't really know what this does, saw it in another plugin, but somehow , this does't work for me.
The problem is the above doesn't work either. I copied it above solution from a GitHub repository, so my question is why does the above solution not work for me and more importantly what is it really doing because this.onClick = this.onClick.bind(this); doesn't make sense to me at all, can somebody break this down for me, please.
P.S. I don't want to use arrow functions to circumvent this problem, that works fine, I know.
Here is a working example of the plugin: JSfiddle.

Mootools Class to Jquery

I'm converting a mootools class to Jquery, but I'm with a problem at the moment.
I've the following code (mootools)
var ListaItens = new Class({
...
...
initialize: function(element){
....
this.btnAdd = this.tabela.getElement('.add_linha button');
if(this.btnAdd){
this.btnAdd.addEvent('click', this.addLinha.bindWithEvent(this));
this.checkAdd();
}
...
},
addLinha: function(){
}
});
Now in Jquery I've this
var ListaItens = function(element, maxLinhas){
...
this.btnAdd = this.tabela.find('.add_linha button')[0];
if(this.btnAdd){
//$(this.btnAdd).proxy('click', this.addLinha);
$(this.btnAdd).on("click", this.addLinha);
this.checkAdd;
}
...
this.addLinha = function(){
}
})
My problem is how to bind the addline function to btnAdd. My code isn't work because the element 'this' change. And I don't know how to convert the function bindWithEvent to jquery.
Any solution?
Thanks in advance
As far as I know, jQuery does not provide a similar concept of classes as mootools does, so one thing you can do is to use the »classic JS approach« to create classes like so:
function ListaItens () {
var that = this;
this.tabela = $(…);
this.btnAdd = this.tabela.find(…);
if (this.btnAdd) {
this.this.btnAdd.on('click', function (e) {
that.addLinha();
})
}
}
ListaItens.prototype.addLinha = function () {
}
var instance = new ListaItens();
So, to answer your question: What you basically need to do is to keep a reference to the »original this«

How do I make my click catcher work?

I'm trying to create a simple click catcher where if you click .image-class the javascript will take the href from another element with a class name of .btn and send you to it's destination. Though I keep getting errors on lines 7 & 10 saying that undefined is not a function. How do I make this work?
<script>
var ClickCatcher=
{
init:function(){
var link = jQuery('.btn')[1].href;
var imgCatch = jQuery('.image-class');
imgCatch.addEventListener("click", ClickCatcher.clickListener, false);
},
clickListener:function(){
window.location = link;
}
};
ClickCatcher.init();
</script>
You can do this with jquery with a simple click event
jQuery('.image-class').on('click', function (){
window.location = jQuery('.btn').eq(1).attr('href');
});
But if you still want to write in the way you have you can do:
var ClickCatcher = {
init: function () {
jQuery('.image-class').on('click', function (){
window.location = jQuery('.btn').eq(1).attr('href');
});
}
};
ClickCatcher.init();
Just make sure to fire the init method after dom load.
update: One issue with it is that you have coded your target etc in the code rather then pass it, so its going to be hard to reuse, you'd be better off doing:
var ClickCatcher = {
init: function ($button, loc) {
$button.on('click', function (){
window.location = loc;
});
}
};
ClickCatcher.init(jQuery('.image-class'), jQuery('.btn').eq(1).attr('href'));
That way the internal working is seperate from the dom (as you are passing the dom dependencies to the function.
#atmd showed a very good way of doing this. If you just want to know what your mistake was though. It is wa an error in your jQuery stament to get the btn href
jQuery('.btn')[1].href
you need to call the attr function and then get the href attr. and use .eq(1) to reduce the set to the first btn
jQuery('.btn').eq(1).attr('href);

Accessing function from within another with Javascript

I'm trying to get the jquery loadmask addon to work that will mask elements (for loading content). I'm using knockout.js, and when if I mask an element outside of my viewmodel it works, but I want to mask it upon submitting a POST request, and then unmask when I receive it. I'm getting an "object has no method mask" error from this. I'm not quite sure how to go about setting up an object to access it.
This works, but it's not what I want. I noted in the code where I would like to call mask from
<div id = "register_container">
<div data-bind="visible: register()">
<div id = "register_form"> <!--this is the div I want to mask -->>
<button data-bind="click: submitRegistration">Submit</button>
</div>
</div>
</div>
function MyViewModel(){
self.submitRegistration = function(){
//I want to mask here. When I try it says Object[object object] has no method mask
$.post....{
if(data.result == success){
// andunmask here
}
}
}
}
$("#register_form").mask("Waiting..."); //the masking works when I place it here, but it's always enabled and I want it inside the viewmodel where I noted so it only works when the POST request is in process
That's great and all, but I want to mask something from inside the viewmodel where I noted. How can I accomplish this?
I see several things that could be the problem.
Frist, you're doing assignment as opposed to comparison in the if statement. Use this instead:
if(data.result == success){
or even
if(data.result === success){
Second is the fact that I don't quite understand your code self.submitRegistration(){, which typically looks more like this:
var MyViewModel = function () {
var self = this;
self.submitRegistration = function() {
};
};
Then, if I mock the $.post call, it would work like this:
var MyViewModel = function () {
var self = this;
self.register = ko.observable(true);
self.submitRegistration = function() {
$("#register_form").mask("Waiting...");
// Mock $.post
window.setTimeout(function () {
if (1 == 1) {
// andunmask here
$("#register_form").unmask();
}
}, 3000);
}
};
ko.applyBindings(new MyViewModel());
See this fiddle for a demo.
You could even have Knockout help you find the element to look for:
See this updated fiddle for a demo of that.
// Use the "event" parameter to find the element...
self.submitRegistration = function(data, event) {
$(event.target).closest('#register_form').mask("Waiting...");
Hope it helps.

Refactoring Code

Let's say I have the following code:
$(function () {
$(".buy-it-now.ribbon").click(function () {
$(".bid-to-beat.ribbon.active").removeClass("active");
$(".bid-to-beat.ribbon").addClass("inactive");
$(".buy-it-now.ribbon.inactive").removeClass("inactive");
$(".buy-it-now.ribbon").addClass("active");
$(".bid-now").hide();
$(".buy-now").show();
$(".add-to-cart").hide();
})
$(".bid-to-beat.ribbon").click(function () {
$(".buy-it-now.ribbon.active").removeClass("active");
$(".buy-it-now.ribbon").addClass("inactive");
$(".bid-to-beat.ribbon").removeClass("inactive");
$(".bid-to-beat.ribbon").addClass("active");
$(".buy-now").hide();
$(".bid-now").show();
$(".add-to-cart").show();
});
});
It is a simple function that allows for multiple UI related things to happen on the front-end of a site I am working on. I am fairly (very) new to jQuery and JavaScript in general and am learning about refactoring and making my code more condensed now. The way I currently write code is sort of line per thought I have. So my question is how would an experienced developer write this same code? Or rather, how could I refactor this code?
Try the following:
$(function () {
var $handlers = $('.buy-it-now.ribbon, .bid-to-beat.ribbon');
$handlers.click(function() {
$handlers.toggleClass("active inactive");
var $elements = $(".bid-now, .add-to-cart"),
$buyElement = $(".buy-now");
if($(this).is('.buy-it-now.ribbon')) {
$elements.hide();
$buyElement.show();
} else {
$elements.show();
$buyElement.hide();
}
});
});
This question would be better suited for codereview, but yes it can be condensed a little using method chaining.
$(function () {
$(".buy-it-now.ribbon").click(function () {
$(".bid-to-beat.ribbon").removeClass("active").addClass("inactive");
$(".buy-it-now.ribbon").removeClass("inactive").addClass("active");
$(".bid-now").hide();
$(".buy-now").show();
$(".add-to-cart").hide();
})
$(".bid-to-beat.ribbon").click(function () {
$(".buy-it-now.ribbon").removeClass("active").addClass("inactive");
$(".bid-to-beat.ribbon").removeClass("inactive").addClass("active");
$(".buy-now").hide();
$(".bid-now").show();
$(".add-to-cart").show();
});
});
You could condense it further by pre selecting the elements and caching them in variables before the click events as long as no elements are added or removed during the life of the page.
As your code it is you can combine some of the selectors into a single line. And also because your elements looks to be static you can cache them into a variable and use them later as it reduces the number of times a element is looked up in the DOM reducing the accessing time..
Also you can limit the scope of these variables or selectors by encasing them in an object or a closure..
Maybe something in these lines..
$(function () {
cart.init();
});
var cart = {
elems : {
$buyRibbon : null,
$bidRibbon : null,
$bidNow: null,
$buyNow: null,
$addToCart: null
},
events : {
},
init : function() {
this.elems.$buyRibbon = $(".buy-it-now.ribbon");
this.elems.$bidRibbon = $(".bid-to-beat.ribbon");
this.elems.$bidNow = $(".bid-now") ;
this.elems.$buyNow = $(".buy-now") ;
this.elems.$addToCart = $(".add-to-cart") ;
this.events.buyClick();
this.events.bidClick();
}
};
cart.events.buyClick = function() {
cart.elems.$buyRibbon.on('click', function(){
cart.elems.$bidRibbon.removeClass('active').addClass('inactive');
cart.elems.$buyRibbon.removeClass('inactive').addClass('active');
cart.elems.$bidNow.hide();
cart.elems.$buyNow.show();
cart.elems.$addToCart.hide();
});
}
cart.events.bidClick = function() {
cart.elems.$bidRibbon.on('click', function(){
cart.elems.$buyRibbon.removeClass('active').addClass('inactive');
cart.elems.$bidRibbon.removeClass('inactive').addClass('active');
cart.elems.$bidNow.show();
cart.elems.$buyNow.hide();
cart.elems.$addToCart.show();
});
}
So basically in here your whole cart is a object ..And the cart has different properties which are related to this.. You follow the principles of object oriented programming here..
Using closures I heard gives you better design limiting the scope of your code..
Might I suggest something like this:
$(function () {
var buyNowButton = $('buy-it-now.ribbon'),
bidToBeatButton = $('.bid-to-beat.ribbon'),
buyNowEls = $('.buy-now'),
bidToBeatEls = $('.bid-now,.add-to-cart');
var toggleButtons = function(showBuyNow){
buyNowButton.toggleClass('active', showBuyNow);
bidToBeatButton.toggleClass('active', !showBuyNow);
buyNowEls.toggle(showBuyNow);
bidToBeatEls.toggle(!showBuyNow);
}
buyNowButton.click(function(){ toggleButtons(true) });
bidToBeatButton.click(function(){ toggleButtons(false) });
});
You could save a some lines by removing the selectors at the start and just do the selection in place, if the saved space would be more important than the minor performance hit. Then it would look like this:
$(function () {
var toggleButtons = function(showBuyNow){
$('buy-it-now.ribbon').toggleClass('active', showBuyNow);
$('.bid-to-beat.ribbon').toggleClass('active', !showBuyNow);
$('.buy-now').toggle(showBuyNow);
$('.bid-now,.add-to-cart').toggle(!showBuyNow);
}
$('buy-it-now.ribbon').click(function(){ toggleButtons(true) });
$('.bid-to-beat.ribbon').click(function(){ toggleButtons(false) });
});
The first version selects the elements once and holds them in memory; the second selects them each time the button is clicked. Both solve the problem I believe would occur with the selected answer where clicking the same button twice would cause the .active and .inactive classes to get out of sync with the shown/hidden elements.

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