Why doesn't my simple Ember.js Handlebars helper work when loading data asynchronously. Writing a helper to check permissions in Ember.js - Livsey.org. Background Lets say we’re writing a blog which allows users to login, but only certain users can write and edit articles. We want to display add/edit buttons based on permissions, so how do we do that?
For simple permissions, this is quite trivial. For example, to check if the current logged in user is an administrator we can just do something like: This only works if we have a single property and we can’t pass any arguments, which means the following won’t work: Research What we want is a version of if which knows about permissions and will let us pass in arguments so that we can end up with something like this: Let’s take a look at from the source and see how if works: This just does some sanity checking and hands off to boundIf: This in turn calls bind which handles setting up all the observers and re-rendering when properties change. It looks like if we create a helper which calls boundIf with some property to observe on an object, it will take care of the rest for us.
Implementation. The client-side templating throwdown: mustache, handlebars, dust.js, and more. In a previous post, we told you how LinkedIn is dumping server-side templates in favor of client-side templates. We've gotten lots of great feedback that we'll discuss in future posts, but today, we'll focus on one question that was especially popular: How did LinkedIn pick dust.js as its client-side templating solution? In the following blog post, we'll outline the requirements we had, the evaluation process, and the results. The candidates The open source community has created a huge number of client-side templating solutions. When we did our initial research, we came up with a list of 26 templating technologies.
This left us with 18 templating technologies to evaluate. Embedded JavaScript Templates These templating options allow you to embed regular JavaScript code directly within the template, an approach similar to ERBs. Logic-less Templates This group of templates follows the philosophy that there should be little to no logic in your templates.
The Test The List The Score Mustache Dust.js. Handlebars.js: Minimal Templating on Steroids. Ember.js nested outlets. Getting Started with Handlebars.js. Web apps are using JavaScript to create dynamic interfaces now more than ever before, and that’s not a trend that will change any time soon. DOM manipulation is great for simpler JavaScript apps, but what do you do when you’re changing huge chunks of the document with each change of the view? That’s where JavaScript templating comes into play. There are quite a few amazing JavaScript templating libraries available. I started out with JavaScript templating using mustache.js, a JavaScript port of the excellent Mustache templating language and moved on to a stint using John Resig’s JavaScript Micro-Templating. jQuery has its official templating plugin, and so does Underscore.js.
Even 37signals has a JavaScript templating language, although it’s for CoffeeScript, called eco. My personal favorite JavaScript templating language these days is Handlebars.js. Why handlebars.js? I have to disclose that I’m a little biased – I worked with Yehuda Katz on Handlebars.js. Installation and Usage Blocks. Ember.js Handlebars View content Inheritance + Image Upload Preview + View Object Binding | Chris Meyers. This tutorial includes: (1) inheriting a parent view’s content context in Handlebars, (2) an ajax image upload preview, and (3) object view 2-way binding. The following fiddle is the full example.
Handlebar provides views the ability to specify a data context for which to interact with. The working context is effectively a passed in argument for use by the view. It’s common to have nested views when dealing with Handlebars and Ember.js. Further, you often want to ‘forward’ the parent context to the nested view. But how do you do this? Providing the user with a preview of an image they intend to upload is a useful feature. See jsfiddle at top of page. Like this: Like Loading...