SVGs from an external source can be rendered via <img> tags, but this has multiple drawbacks: you can't customize the fill, use CSS variables, or use focus/hover states.
SVG loader is a simple JS code you can include that fetches SVGs using XHR and injects the SVG code in the tag's place, giving you best of both worlds: externally stored SVGs (e.g, on CDN) and inline SVGs.
It's super-tiny, works well with frameworks and has minimal to no impact on performance.
SVG Loader is designed to be plug and play. Hence, all you need to is to include the loader JS anywhere in your code, and then start using the code like this:
<!--
Include this script anywhere in your code, preferably <HEAD> so
icons can be fetched faster.
-->
<script type="text/javascript" src="svg-loader.min.js" async></script>
<!-- Use an external SVG -->
<svg
data-src="https://unpkg.com/@mdi/[email protected]/svg/star.svg"
width="50"
height="50"
fill="red"></svg>
<svg
data-src="https://unpkg.com/@mdi/[email protected]/svg/heart.svg"
width="50"
height="50"
fill="red"></svg>
<svg
data-src="https://unpkg.com/@mdi/[email protected]/svg/cog.svg"
width="50"
height="50"
fill="currentColor"
style="color: purple;"></svg>Note: Because SVG Loader fetches file using XHRs, it's limited by CORS policies of the browser.
So you need to ensure that correct Access-Control-Allow-Origin headers are sent with the file being served or that the files are hosted on your own domain.
The library is framework/platform agnostic. You should be able to use it in React, Vue.js and others as long as you're using the correct attributes.
npm install external-svg-loader
Then, in your app, require/import external-svg-loader anywhere. Here's an example:
import React from "react";
import ReactDOM from "react-dom";
import "external-svg-loader";
class App extends React.Component {
render() {
return (
<svg
data-src="https://s2.svgbox.net/materialui.svg?ic=mail"
fill="currentColor"
width="50px"
height="50px"
style={{
color: "red"
}}
/>
);
}
}
ReactDOM.render(<App />, document.getElementById("container"));SVG loader can also be included via unpkg CDN. Example:
<script type="text/javascript" src="https://unpkg.com/external-svg-loader@latest/svg-loader.min.js" async></script>By default, the XHR response is cached for 24 hours, so that any subsequent loads are instantenous. You can disable this behavior by passing data-cache="disabled". You can also modify
the caching period by passing number of seconds. Example:
<svg
data-src="https://unpkg.com/@mdi/[email protected]/svg/heart.svg"
data-cache="604800"
width="50"
height="50"></svg><svg
data-src="https://unpkg.com/@mdi/[email protected]/svg/heart.svg"
data-cache="21600"
width="50"
height="50"></svg><svg
data-src="https://unpkg.com/@mdi/[email protected]/svg/heart.svg"
data-cache="disabled"
width="50"
height="50"></svg>SVG format supports scripting. However, for security reasons, svg-loader will strip all JS code before injecting the SVG file. You can enable it by:
<svg
data-src="https://unpkg.com/@mdi/[email protected]/svg/heart.svg"
data-js="enabled"
onclick="alert('clicked')"
width="50"
height="50"
fill="red"></svg>To prevent conflicts between conflicting identifiers of different SVGs, svg-loader scopes the identifiers and styling rules by adding prefixes.
You can disable this behavior by:
<svg
data-src="https://unpkg.com/@mdi/[email protected]/svg/heart.svg"
data-unique-ids="disabled"
width="50"
height="50"
fill="red"></svg><svg
data-src="https://unpkg.com/@mdi/[email protected]/svg/heart.svg"
data-css-scoping="disabled"
width="50"
height="50"
fill="red"></svg>You can also lazy load icons by using data-loading=lazy. This will make icon not load until it's about to enter the viewport. For lazy loading, external-svg-loader uses Intersection Observer API.
<svg
data-src="https://unpkg.com/@mdi/[email protected]/svg/heart.svg"
data-loading="lazy"
width="50"
height="50"></svg>When the SVG has been loaded an event iconload is triggered. This can be used to get the references to the loaded SVG element and do some further processing. You can also use the oniconload inline function.
<svg
data-src="https://unpkg.com/@mdi/[email protected]/svg/cog.svg"
oniconload="console.log('Icon loaded', this)"></svg><svg data-src="https://unpkg.com/@mdi/[email protected]/svg/cog.svg"></svg>
<script>
window.addEventListener('iconload', (e) => {
if (e.target.id === 'iconload') {
console.log('Icon loaded', e.target);
}
});
</script>React doesn't support custom events out of the box. To circumvent this limitation, you can refs.
class MyApp extends React.Component {
constructor(props) {
super(props);
this.ref = React.createRef()
}
render() {
return (<svg data-src="https://unpkg.com/@mdi/[email protected]/svg/cog.svg" ref={this.ref}></svg>);
}
componentDidMount() {
this.ref.current.addEventListener('iconload', () => {
console.log("Icon Loaded", this.ref.current)
})
}
}MIT