Develop Reference

Backbone event click on table row

I created a view for table row, that i want to listen to any click on any cells in this row.
This is how I implemented:
let ListItem = Backbone.View.extend({
events: {
'click tr': 'showDetails',
'click': 'showDetails'
},
template: function() {
return "<tr><td><img src=<%= imageUrl %> /></td><td class='name'><%= firstName %></td><td><%= lastName %></td><td><%= homeTown %></td><td><button type='button' id='ddd' class='btn btn-danger'>Delete</button></td></tr>";
},
render: function() {
var oTemplate = _.template(this.template());
this.$el.html(oTemplate(this.model.toJSON()));
$('table > tbody:last-child').append(this.$el.html());
return this;
},
showDetails: function() {
alert("*****");
},
hide: function(bToHide, index) {
index++;
if (!bToHide) {
$($('tr')[index]).show();
return;
}
$($('tr')[index]).hide();
this.rendered = true;
},
openActorView: function() {
window.open('/#actor/' + window.actorsCollection.indexOf(this.model), '_self');
}
});
After clicking the row\cells within, nothing happens.
I listen to click on this view + click on the tr, but nothing happens.
Also, when add event to tr td nothing happens ether.
Thanks for helping

The reason it doesn't work
$('table > tbody:last-child').append(this.$el.html());
The jQuery .html() function returns a string.
So you're creating a nice Backbone view, with easy to define event listeners, then you don't use it, you just take its string representation and dump it in the DOM, losing any event listeners previously bound.
The improvements
First, there's no need to make the template a function, just use _.template directly. I wrote another answer which provides additional information on how to use _.template.
After that, don't use global selectors inside a view. It kills the purpose of a scoped component view. Let the parent view class deals with this.
let ListItem = Backbone.View.extend({
tagName: 'tr', // the list item is a `<tr>`
events: {
'click': 'showDetails'
},
template: _.template("<td><img src=<%= imageUrl %> /></td><td class='name'><%= firstName %></td><td><%= lastName %></td><td><%= homeTown %></td><td><button type='button' id='ddd' class='btn btn-danger'>Delete</button></td>"),
render: function() {
this.$el.html(this.template(this.model.toJSON()));
return this;
},
showDetails: function() {
console.log("show details event");
}
});
Make a list view that manages the table. This is the parent class that will put the list items into the DOM.
Instead of using the jQuery core function, use the Backbone view scoped alias this.$() to cache the table body.
let ListView = Backbone.View.extend({
initialize: function() {
this.$body = this.$('tbody');
},
render: function() {
this.$body.empty();
this.collection.each(this.renderItem, this);
return this;
},
renderItem: function(model) {
var view = new ListItem({ model: model });
this.$body.append(view.render().el); // use the DOMElement
}
});
Then pass an existing table from outside the view.
new ListView({ el: 'table.my-table' }).render();
This is a super basic example and you should be aware that performance could be improved further and that it could leak memory if used as-is.
See how to improve list rendering performance with Backbone.

Backbone view events do not fire

I have a simple backbone view as follows:
/**
* Renders a form view for an event object.
*/
APP.EventFormView = Backbone.View.extend({
tagName: 'form',
events: {
'keydown': 'keyPressed',
'focus input': 'inputChanged',
'change select': 'selectChanged',
'change textarea': 'textareaChanged'
},
initialize: function() {
this.template = _.template($('#newevent-form').html());
this.listenTo(this.model, 'change', this.render);
this.listenTo(APP.eventTypes, 'update', this.render);
this.listenTo(APP.selectedEvent, 'update', this.render);
},
render: function() {
var modelJSON = this.model.toJSON();
if ('id' in modelJSON && modelJSON.id !== "") {
this.loadForm();
} else if (!('id' in modelJSON) || modelJSON.id === "") {
this.loadForm();
} else {
this.$el.html('');
}
return this;
},
loadForm: function() {
var templateData = $.extend(this.model.toJSON(),
{"event_types":APP.eventTypes.toJSON()});
this.$el.html('');
this.$el.html(this.template($.extend(this.model.toJSON(),
{event_types: APP.eventTypes.toJSON()})));
$('.ev-main-container').html('').html(this.el);
},
inputChanged: function(e) {
console.log('inputChanged');
},
selectChanged: function(e) {
console.log('selectChanged');
},
textareaChanged: function(e) {
console.log('textareaChanged');
},
keyPressed: function(e) {
console.log('key pressed');
}
});
I initialize this view as follows under document.ready:
// Initialize the form view
APP.selectedEvent = APP.selectedEvent || new APP.Event();
APP.eventFormView = new APP.EventFormView({model: APP.selectedEvent});
APP.eventFormView.render();
But none of the events I have defined are firing for some reason, What is it that I am doing wrong here ?
Update:
Ok, I fugred out if i remove $('.ev-main-container').html('').html(this.el); from the loadForm method and instead intialize the view as follows, it works:
APP.eventFormView = new APP.EventFormView({
model: APP.selectedEvent,
el: $('.ev-main-container'),
});
I was able to resolve it but I still don't understand why this happens, could anyone throw a little light on what's going on and how this works.

jQuery's html function has a side effect that many people seem to forget about, from the fine manual:
jQuery removes other constructs such as data and event handlers from child elements before replacing those elements with the new content.
Consider what that means when you do something like this:
container.html(view.el);
container.html(view.el);
Everything will be fine after the first container.html() call. But the second will "remove ... event handlers from child elements" (such as view.el) before adding the new content. So after the second container.html() call, all the events on view.el are gone. Sound familiar?
You have lots of things that will call render on your view and render will eventually do this:
$('.ev-main-container').html('').html(this.el);
Your events will silently disappear the second time that gets called but the HTML will look just fine.
Consider this simplified example (http://jsfiddle.net/ambiguous/otnyv93e/):
var V = Backbone.View.extend({
tagName: 'form',
events: {
'click button': 'clicked'
},
initialize: function() {
this.template = _.template($('#t').html());
},
render: function() {
this.$el.html('');
this.$el.html(this.template());
$('.ev-main-container').html('').html(this.el);
return this;
},
clicked: function() {
console.log('clicked');
}
});
var v = new V;
v.render();
$('#re-render').click(function() {
v.render();
console.log('Re-rendered');
});
and you'll see exactly your problem.
If you make the view's el the .ev-main-container then you'll be using html() to alter the contents of el rather than altering the contents of the element that contains el. Once you're working entirely inside the el you're no longer accidentally re-using an element and no longer accidentally removing the event bindings from that element.
My rules of thumb for preventing event problems with Backbone:
Never attach views to existing DOM nodes, always let views create and own their own el and let the caller put that el in a container.
Call remove on views to dispose of them when they're no longer needed.
Don't try to re-use views, create them when you need them and remove them when you don't need them.
No view references anything outside its el.
There are exceptions (of course) and this approach won't solve everything but it is a good starting point and avoids most of the common problems.

How turn off all events before new view rendering

I have several views.
In some of them I have the similar events like
events: {
'click #save': 'save'
}
When I create and render new view old event listening remains so old algorythm still works when I already change the view.
As I know there is a stopListening() function but how can I activate for all previous views.
So when I change the view/page I want disable all previous events.
How I can do that?

ID's are global, you shouldn't have more than one per page. Append your events to a class instead.
events: {
'click .save-btn': 'save'
}
Also, make sure you're disposing your views once you finished using them:
var MyView = Backbone.View.extend({
events: {
'click .save-btn': 'save'
},
...
dispose: function() {
this.unbind();
this.remove();
}
};
var view = MyView();
...
view.dispose();
Cheers.

try to use el.
var MyView = Backbone.View.extend({
el: '#wrapper_of_save_element',
events: {
'click #save': 'save'
},
save: function() {
...
}
});
so your event is only inside your #wrapper_of_save_element (eg. a wrapper div)
http://backbonejs.org/#View-el

Re-inject Backbone.View into the DOM with keeping events instead of creating new events

I got following example Backbone.View:
var View = Backbone.View.extend({
tagName: "div",
className: "advertisement",
initialize: function () {
this.on('switch', this.
switch, this);
this.views = {};
this.views.laptop = new LaptopAdView();
this.views.piano = new PianoAdView();
this.views.food = new FoodAdView();
},
render: function () {
this.$el.empty();
this.
switch ('laptops');
return this;
},
switch: function (ad) {
var el;
if (ad === 'laptop') {
el = this.views.laptop.render().el;
} else if (ad === 'piano') {
el = this.views.piano.render().el;
} else {
el = this.views.food.render().el;
}
// reinsert the chosen view
this.$el.empty().append(el);
// bind all events new
this.delegateEvents();
}
});
As you see I use this.delegatEvents() to recreate all event bindings. This is actually not a perfect solution... It would be far better when I use this.$el.detach(); or an other method so I cache the whole object with its event instead of re-rendering and recreating all events.
Now with working fiddle:
http://jsfiddle.net/RRXnK/66/

You are trying to bind to a Backbone view instead of a DOM element:
this.on('switch', this.switch, this);
It's all good, but who triggers 'switch' event? You do not have bindings that trigger DOM events, and this.delegateEvents(); only works on DOM events.
Once you set up DOM events, e.g.
this.$el.on('click', 'a', this.switch) -- 'switch' event will be triggered, and you will NOT have to re-delegate events as long as $el is in not removed from DOM.

Backbone.js views - binding event to element outside of "el"

The 2nd answer to this question nicely explains how event declarations in Backbone.js views are scoped to the view's el element.
It seems like a reasonable use case to want to bind an event to an element outside the scope of el, e.g. a button on a different part of the page.
What is the best way of achieving this?

there is not really a reason you would want to bind to an element outside the view,
there are other methods for that.
that element is most likely in it's own view, (if not, think about giving it a view!)
since it is in it's own view, why don't you just do the binding there, and in the callback Function,
use .trigger(); to trigger an event.
subscribe to that event in your current view, and fire the right code when the event is triggered.
take a look at this example in JSFiddle, http://jsfiddle.net/xsvUJ/2/
this is the code used:
var app = {views: {}};
app.user = Backbone.Model.extend({
defaults: { name: 'Sander' },
promptName: function(){
var newname = prompt("Please may i have your name?:");
this.set({name: newname});
}
});
app.views.user = Backbone.View.extend({
el: '#user',
initialize: function(){
_.bindAll(this, "render", "myEventCatcher", "updateName");
this.model.bind("myEvent", this.myEventCatcher);
this.model.bind("change:name", this.updateName);
this.el = $(this.el);
},
render: function () {
$('h1',this.el).html('Welcome,<span class="name"> </span>');
return this;
},
updateName: function() {
var newname = this.model.get('name');
console.log(this.el, newname);
$('span.name', this.el).text(newname);
},
myEventCatcher: function(e) {
// event is caught, now do something... lets ask the user for it's name and add it in the view...
var color = this.el.hasClass('eventHappened') ? 'black' : 'red';
alert('directly subscribed to a custom event ... changing background color to ' + color);
this.el.toggleClass('eventHappened');
}
});
app.views.sidebar = Backbone.View.extend({
el: '#sidebar',
events: {
"click #fireEvent" : "myClickHandler"
},
initialize: function(){
_.bindAll(this, "myClickHandler");
},
myClickHandler: function(e) {
window.user.trigger("myEvent");
window.user.promptName();
}
});
$(function(){
window.user = new app.user({name: "sander houttekier"});
var userView = new app.views.user({model: window.user}).render();
var sidebarView = new app.views.sidebar({});
});

Update: This answer is no longer valid/right. Please see other answers below!
Why do you want to do this?
Apart from that, you could always just bind it using regular jQuery handlers. E.g.
$("#outside-element").click(this.myViewFunction);
IIRC, Backbone.js just uses the regular jQuery handlers, so you're essentially doing the same thing, but breaking the scope :)