Say hello to GravyBind! This utility lets you bind things in your HTML to JavaScript variables.
Let me start off by saying that this is not a good alternative to anything more fully-featured like Vue
or React. This is meant for simple scenarios where you want to just add some dynamism to an application
that's either simpler or older without making major changes or making a big mess.
In the case I originally created this for, we had a .NET Core MVC project with jQuery spaghetti that was
quickly becoming a nightmare to maintain as the app's complexity increased. I needed a simple way to
update things like display values, class bindings, and native HTML validation properties in a more
declarative way than a bunch of random query selectors. GravyBind uses data attributes to handle
binding, so your markup and bindings are in the same place and it's easy to see how things are
connected. There is no change tracker, it literally refreshes all the bindings when you tell it to so
this probably isn't the most optimized thing around. Feel free to open a pull request if you have some
performance improvements in mind.
Again, if you're building a new app, I strongly recommend using a popular frontend framework or library.
However when limitations prevent that, this can come in handy.
With that out of the way, let's take a look at what this can do!
Add a reference to the script
<script type="text/javascript" src="https://unpkg.com/gravy-bind/dist.browser/index.js"></script>
Create a binder
const binder = new GravyBinder();
Or provide a variable scope (default is just window)
const binder = new GravyBinder({firstName: '', lastName:''});
Or limit scanning to just part of the DOM tree
const binder = new GravyBinder(myScope, document.getElementById('rootNode'));
Data tag | Direction | Description |
---|---|---|
data-in | Inward | Captures value from an input |
data-display | Outward | Outputs content to innerHTML |
data-min | Outward | Binds to min attribute of input |
data-max | Outward | Binds to max attribute of output |
data-disable | Outward | Controls disabled state of element |
data-out | Outward | Sets the value of an input |
data-class/data-class-condition | Outward | Applies the specified class when the condition is true |
data-hide | Outward | Controls hidden state of element |
data-show | Outward | Controls hidden state of element (inverse of data-hide) |
data-min-length | Outward | Controls the minLength of an input |
data-max-length | Outward | Controls the maxLength of an input |
data-required | Outward | Controls the required attribute of an input |
data-placeholder | Outward | Binds to the placeholder of an input |
data-checked | Outward | Binds to the checked attribute of a checkbox |
data-step | Outward | Controls the step of a range or number input |
data-title | Outward | Sets the title attribute of a node |
data-href | Outward | Sets the href of an anchor |
This is an example of the JavaScript that things in this demo are bound to. It's defined by a class but you can use any object you like.
Use a display: none class to hide stuff
<input type="checkbox" data-in="this.toggleColor">
<div data-class="bg-success" data-class-condition="this.toggleColor">
Change the color
</div>
<input data-in="this.textInput" type="text">
<span data-display="this.textInput">
<span data-display="this.getStupidText(this.textInput)"></span>
<input type="checkbox" data-in="this.checkInput">
<span data-display="this.checkInput"></span>
<span data-display="this.checkInput ? 'Yes' : 'No'"></span>
Useful for setting hidden inputs to be submitted with a form
<select data-in="this.select">
<option selected disabled value="">Open this select menu</option>
<option value="Eeny">One</option>
<option value="Meeny">Two</option>
<option value="Miny">Three</option>
<option value="Moe">Four</option>
</select>
<input data-out="this.select" disabled>
<input data-in="this.min" type="number">
<input data-in="this.max" type="number">
<input data-min="this.min" data-max="this.max" data-in="this.range" type="range">
<span data-display="this.range"></span>
<input data-min="this.min" data-max="this.max" type="number">
<input type="checkbox" data-in="this.disable">
<button data-disable="this.disable">Button :)</button>
By default, text inputs update on change or blur events. If you aren't worried about the performance implications and need something faster, you can add a data-immediate attribute to the element.
<input type="text" data-in="this.immediate" data-immediate"true">
<span data-display="this.getStupidText(this.immediate)"></span>
You can manually trigger a display refresh by calling updateOutwardBindings on your binder instance. This is useful if you changed some values via code or fetched some info in asynchronously.
<button onclick="dm.triggerRefresh()">Trigger update</button>
<span data-display="this.counter"></span>
Additional bindings can be added by calling the registerOutwardBinding method on a GravyBinder. Pass in the name of the data attribute to use in kebab-case and an action to perform with the node and value when bindings are updated.
this.binder.registerOutwardBinding('alt', (element, value) => element.alt = value);
this.binder.registerOutwardBinding('src', (element, value) => element.src = value);
getImageUrl = () => `https://via.placeholder.com/${this.width}x${this.height}`;
<input type="text" data-in="this.alt">
<input type="number" data-in="this.width" id="width">
<input type="number" data-in="this.height" id="height">
<img data-src="this.getImageUrl()" data-alt="this.alt" data-title="this.alt">