This article covers the portal attribute plugin for Aurelia. This plugin is created for managing rendering flow of part of custom element in an Aurelia application. The plugin supports the use of dynamic elements matching as render target, via either element references or CSS selectors. Online Demo
npm install aurelia-portal-attribute --saveIf you use JSPM, install the plugin via jspm with following command
jspm install aurelia-portal-attribute- Make sure you use manual bootstrapping. In order to do so open your
index.htmland locate the element with the attribute aurelia-app. Change it to look like this:
<body aurelia-app="main">...</body>- In
main.jsin yoursrc:
export function configure(aurelia) {
aurelia.use
.standardConfiguration()
.plugin(PLATFORM.moduleName('aurelia-portal-attribute'))
aurelia.start().then(a => a.setRoot());
}There are a few scenarios you can take advantage of the attribute.
- There is part of the element that needs to be rendered into document body.
This is a common case, as the component may be nested under a
overflow: hiddenancestor and it won't be able to display properly. Consider the following dom structure of a custom<combobox />element:
<template class="combobox">
<div class="input-ct">
<input ref="input" value.bind="filterText" />
<div>
<ul class="list-group items-list">
<li repeat.for="item of items | filter: filterText" class="list-group-item">${item.name}</li>
</ul>
</template>This structure often works fine when we have ul.list-group.item-list CSS: position: absolute; top: 100%; But it will not work when the custom element is nested inside an element with overflow: hidden, or inside an element with scroll, like following example:
<!-- app.html -->
<div style="height: 200px; overflow: auto;">
<!-- oopps, my list got clipped -->
<combobox></combobox>
</div>A simple solution is to use CSS: position: fixed on the list and calculat its position, or the portal attribute like the following example:
<template class="combobox">
<div class="input-ct">
<input ref="input" value.bind="filterText" />
<div>
<ul portal class="list-group items-list">
<li repeat.for="item of items | filter: filterText" class="list-group-item">${item.name}</li>
</ul>
</template>portal attribute may seem to be an overkill, but beside styling, it also helps you separate DOM path of different parts in your custom element,
whist still binds them to the same underlying view model, which should helps better DOM manangement, including event model in some cases.
Following is an example of final rendered DOM tree for <combobox/> above:
<body>
<app>
<combobox>
<!-- combobox internal elements -->
</combobox>
</app>
<!-- combobox item list in the body -->
<ul class="list-group items-list">
<li class="list-group-item">item 1</li>
<li class="list-group-item">item 2</li>
<li class="list-group-item">item 3</li>
...
<!-- more items -->
</ul>
</body>| Name | Types | Default | Description |
|---|---|---|---|
| target | string/Element | undefined | Target of the portal, by default will be resolved to document body, if target cannot be found. If a string is supplied, it will be used to determine the real target with a call document.querySelector() |
| position | beforebegin or afterbegin or beforeend or afterend |
beforeend |
Describing the position relative to the target of a portal to move the content to |
Portalling an element to document body
<div class="my-menu" portal>
or
<div class="my-menu" portal="body">Portalling multiple elements to the end of document body
<template portal>
<p>paragraph 1</p>
<p>paragraph 2</p>
</template>To build the code, follow these steps.
- Ensure that NodeJS is installed. This provides the platform on which the build tooling runs.
- From the project folder, execute the following command:
npm install- To build the code, you can now run:
npm run build- You will find the compiled code in the
distfolder, available in three module formats: AMD, CommonJS and ES6.
npm testThanks goes to Dwayne Charrington for his Aurelia-TypeScript starter package https://github.com/Vheissu/aurelia-typescript-plugin