Before you get started with react-imgix, it's _highly recommended_ that you read Eric Portis' seminal article on srcset and sizes. This article explains the history of responsive images in responsive design, why they're necessary, and how all these technologies work together to save bandwidth and provide a better experience for users. The primary goal of react-imgix is to make these tools easier for developers to implement, so having an understanding of how they work will significantly improve your react-imgix experience.
Below are some other articles that help explain responsive imagery, and how it can work alongside imgix:
- Using imgix with . Discusses the differences between art direction and resolution switching, and provides examples of how to accomplish art direction with imgix. - Responsive Images with srcset and imgix. A look into how imgix can work with srcset and sizes to serve the right image.
This module exports two transpiled versions. If a ES6-module-aware bundler is being used to consume this module, it will pick up an ES6 module version and can perform tree-shaking. If you are not using ES6 modules, you don't have to do anything
Usage
``js import Imgix from "react-imgix";
// in react component ; `
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#### Basic Use Case
For simply using as you would use an , react-imgix can be used as follows:
Please note: 100vw is an appropriate sizes value for a full-bleed image. If your image is not full-bleed, you should use a different value for sizes. Eric Portis' "Srcset and sizes" article goes into depth on how to use the sizes attribute.
Since imgix can generate as many derivative resolutions as needed, react-imgix calculates them programmatically, using the dimensions you specify. All of this information has been placed into the srcset and sizes attributes.
Width and height known and fixed: If the width and height are known beforehand, and a fixed-size image is wanted, it is recommended that they are set explicitly:
`js import Imgix from "react-imgix";
src="https://assets.imgix.net/examples/pione.jpg" width={100} // This sets what resolution the component should load from the CDN and the size of the resulting image height={200} />; `
When width and height are specified, will give the image a srcset with resolution descriptors.
Width and height known but fluid: If the image's intrinsic width and height are known but a fluid size image is wanted, width and height should still be set to avoid layout shift, but they must be set via htmlAttributes so as not to hint to to produce resolution descriptors in the srcset.
`js import Imgix from "react-imgix";
src="https://assets.imgix.net/examples/pione.jpg" sizes="(min-width: 1024px) 40vw, 90vw" htmlAttributes={{ // These are ignored by Imgix but passed through to the element width: 200, height: 100, }} />; `
In this example, will produce a srcset with width descriptors.
#### Server-Side Rendering
> Note This library does not run in Server Components but instead adds the "use client" directive to components. This means they are able to be used alongside Server Components (for example, as children), but they still require client-side JavaScript. Client Components are still SSRed.
React-imgix also works well on the server. Since react-imgix uses srcset and sizes, it allows the browser to render the correctly sized image immediately after the page has loaded. If they are known, pass width and height attributes via htmlAttributes to help combat layout shift.
If the width and height are known beforehand, and a fixed-size image is wanted, set width and height and do not set sizes:
`js import Imgix from "react-imgix";
src="https://assets.imgix.net/examples/pione.jpg" width={100} // This sets what resolution the component should load from the CDN and the size of the resulting image height={200} />; `
#### Flexible Image Rendering
This component acts dynamically by default. The component will leverage srcset and sizes to render the right size image for its container. This is an example of this responsive behaviour.
sizes should be set properly for this to work well, and some styling should be used to set the size of the component rendered. Without sizes and correct styling the image might render at full-size.
Aspect Ratio: A developer can pass a desired aspect ratio, which will be used when generating srcsets to resize and crop your image as specified. For the
ar parameter to take effect, ensure that the fit parameter is set to crop.`js
width:height. Either dimension can be an integer or a float. All of the following are valid: 16:9, 5:1, 1.92:1, 1:1.67.
#### Fixed Image Rendering (i.e. non-flexible)
If the fluid, dynamic nature explained above is not desired, the width and height can be set explicitly.
`js import Imgix from "react-imgix";
src="https://assets.imgix.net/examples/pione.jpg" width={100} // This sets what resolution the component should load from the CDN and the size of the resulting image height={200} />;
`
Fixed image rendering will automatically append a variable
q parameter mapped to each dpr parameter when generating a srcset. This technique is commonly used to compensate for the increased filesize of high-DPR images. Since high-DPR images are displayed at a higher pixel density on devices, image quality can be lowered to reduce overall filesize without sacrificing perceived visual quality. For more information and examples of this technique in action, see this blog post. This behavior will respect any overriding q value passed in via imgixParams and can be disabled altogether with the boolean property disableQualityByDPR.`js src="https://domain.imgix.net/image.jpg" width={100} disableQualityByDPR /> `
Images can be rendered as a background behind children by using
. The component will measure the natural size of the container as determined by the CSS on the page, and will render an optimal image for those dimensions.
// In Component (React) import { Background } from 'react-imgix'
Blog Title
`
This component shares a lot of props that are used in the main component, such as
imgixParams, and htmlAttributes.
As the component has to measure the element in the DOM, it will mount it first and then re-render with an image as the background image. Thus, this technique doesn't work very well with server rendering. If you'd like for this to work well with server rendering, you'll have to set a width and height manually.
Set width and height:
Setting the width and/or height explicitly is recommended if you already know these beforehand. This will save the component from having to do two render passes, and it will render a background image immediately.
This is accomplished by passing
w and h as props to imgixParams.`jsx src="https://.../image.png" imgixParams={{ w: 1920, h: 500 }} className="blog-title" >
A warning is displayed when no fallback image is passed. This warning can be disabled in special circumstances. To disable this warning, look in the warnings section.
#### ImgixProvider Component
The
Higher Order Component (HOC), makes its props available to any nested component in your React application.
For example, by rendering
at the top level of your application with imgixParams defined, all your components will have access to the same imgixParams.`jsx import React from "react"; import Imgix, { ImgixProvider } from "react-imgix"; import HomePage from "./components/HomePage";
You can take advantage of this behavior to use partial URLs with the
component. By defining the domain prop on the Provider, it can be made accessible to all nested components.`jsx // inside App.jsx { /... / }
{/ ... /}s
; { /... / } `
Both the
components above will access to the domain prop from the provider and have their relative src paths resolve to the same domain. So that the generated HTML looks something like:`html
makes accessible can also be overridden by components. Any prop defined on the component will override the value set by the Provider.`jsx // inside App.jsx { /... / }
ImgixProvider components to ensure that different consumers have different props.
For example to give
Imgix components different props from Picture components, you can nest an ImgixProvider inside of another one.
The nested Provider will change the Context for the
Picture component, essentially removing their access to the shared props provided by the root ImgixProvider.`jsx import React from 'react' import Imgix, { ImgixProvider, Picture, Source } from "react-imgix"; export default function simpleImage() { return (
{/ there props will be accessible to all the imgix components /} domain="assets.imgix.net" src="/examples/pione.jpg" imgixParams={{ fit: "crop" }} > {/ since we define a new provider here, the context is redefined for any child components /} > {/ imgixParams prop is no longer defined here /} width={100} htmlAttributes={{ media: "(min-width: 768px)" }} /> width={200} htmlAttributes={{ media: "(min-width: 800px)" }} />
) } `
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#### General Advanced Usage
Although imgix is open to feature suggestions, we might not accept the feature if it is a very specific use case. The features below are examples of what we consider general advanced use cases. Our target here is to support 95% of all the usages of normal
img, picture, and source elements.
If your desired feature falls outside this percentage, do not worry! You will probably still be able to achieve your feature with react-imgix's more powerful API:
buildURL.
This library exposes a pure function,
buildURL, for generating full imgix URLs given a base URL and some parameters.`jsx import { buildURL } from "react-imgix";
This property has strong browser support, and functions without additional JavaScript. Additionally, using browser-level lazy loading enables optimization of the sizes attribute with
If you need granular control over lazy-loading behavior such as loading distance, you can use the Intersection Observer API.
If you are using a library like lazysizes, you can tell the Imgix component to generate compatible attributes instead of the standard
src, srcset, and sizes by changing some configuration settings:`jsx className="lazyload" src="..." sizes="..." attributeConfig={{ src: "data-src", srcSet: "data-srcset", sizes: "data-sizes", }} /> `
The same configuration is available for
components
NB: It is recommended to use the attribute change plugin in order to capture changes in the data-\* attributes. Without this, changing the props to this library will have no effect on the rendered image.
If you'd like to use LQIP images, like before, we recommend using lazysizes. In order to use react-imgix with lazysizes, you can simply tell it to generate lazysizes-compatible attributes instead of the standard
src, srcset, and sizes by changing some configuration settings, and placing the fallback image src in the htmlAttributes:`jsx className="lazyload" src="..." sizes="..." attributeConfig={{ src: "data-src", srcSet: "data-srcset", sizes: "data-sizes", }} htmlAttributes={{ src: "...", // low quality image here }} /> `
NB: If the props of the image are changed after the first load, the low quality image will replace the high quality image. In this case, the
src attribute may have to be set by modifying the DOM directly, or the lazysizes API may have to be called manually after the props are changed. In any case, this behaviour is not supported by the library maintainers, so use at your own risk.
#### Attaching Ref to DOM Elements
A
ref passed to react-imgix using will attach the ref to the instance, rather than the DOM element. It is possible to attach a ref to the DOM element that is rendered using htmlAttributes:`js `
This works for Source and Picture elements as well.
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#### Shared Props (Imgix, Source)
These props are shared among Imgix and Source Components
##### src :: string, required
Usually in the form:
https://[your_domain].imgix.net/[image]. Don't include any parameters.
##### domain :: string, optional
Required only when using partial paths as
src prop for a component. IE, if src is "/images/myImage.jpg", then the domain prop needs to be defined.
Specified the developer's expected size of the image element when rendered on the page. Similar to width. E.g.
100vw, calc(50vw - 50px), 500px. Highly recommended when not passing width or height. Eric Portis' "Srcset and sizes" article goes into depth on how to use the sizes attribute.
##### className :: string
className applied to top level component. To set className on the image itself see htmlAttributes.
##### height :: number
Force images to be a certain height.
##### width :: number
Force images to be a certain width.
##### disableSrcSet :: bool, default = false
Disable generation of variable width src sets to enable responsiveness.
##### disableLibraryParam :: bool
By default this component adds a parameter to the generated url to help imgix with analytics and support for this library. This can be disabled by setting this prop to
true.
##### disablePathEncoding :: bool
By default this component encodes the url path in the src and srcSet. This can be disabled by setting this prop to
true. For more information about how imgix path encoding works, please refer to the imgix/js-core docs.
##### htmlAttributes :: object
Any other attributes to add to the html node (example:
alt, data-*, className).
##### onMounted :: func
Called on
componentDidMount with the mounted DOM node as an argument.
##### attributeConfig :: object
Allows the src, srcset, and sizes attributes to be remapped to different HTML attributes. For example:
src. This is also how width and height can be explicitly set. For more information about this, see the "Background" section above.
_For example_:
`js `
##### className :: string
className applied to top level component. To set className on the image itself see htmlAttributes.
##### disableLibraryParam :: bool
By default this component adds a parameter to the generated url to help imgix with analytics and support for this library. This can be disabled by setting this prop to
true.
##### htmlAttributes :: object
Any other attributes to add to the html node (example:
alt, data-*, className).
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#### Warnings
This library triggers some warnings under certain situations to try aid developers in upgrading or to fail-fast. These can sometimes be incorrect due to the difficulty in detecting error situations. This is annoying, and so there is a way to turn them off. This is not recommended for beginners, but if you are using custom components or other advanced features, it is likely you will have to turn them off.
Warnings can be turned off with the public config API,
PublicConfigAPI, which is exported at the top-level.`js // in init script/application startup import { PublicConfigAPI } from "react-imgix";
PublicConfigAPI.disableWarning('');
//... rest of app startup React.render(...);
`
Warnings can also be enabled with
PublicConfigAPI.enableWarning('')
The warnings available are:
|
warningName | Description | | -------------- | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | | fallbackImage | Triggered when there is no or at the end of the children when using . A fallback image is crucial to ensure the image renders correctly when the browser cannot match against the sources provided | | sizesAttribute | This library requires a sizes prop to be passed so that the images can render responsively. This should only turned off in very special circumstances. | | invalidARFormat | Warnings thrown when the ar imgix parameter is not passed in the correct format (w:h) | | oversizeImage | A runtime error triggered when an image loads with an intrinsic size substantially larger than the rendered size. | | lazyLCP | A runtime error triggered when an image is detected to be the LCP element but is loaded with loading="lazy". |
Upgrade Guides
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This release brings the react-imgix API more in-line with that of imgix's rendering service.
The largest change users will notice is that this project's component will no longer generate a default
fit=crop parameter. The original intention behind this was that generated images would maintain aspect ratio when at least one of the dimensions were specified. However, the default imgix API behavior sets fit=clip, which is now reflected in this project. Although this may not cause breaking changes for all users, it can result in unusual rendered image behavior in some cases. As such, we would rather err on the side of caution and provide users the ability to opt in to these changes via a major release.
If you are currently relying on the default generation of
fit=crop when rendering images, you will now have to manually specify it when invoking the component:`jsx src="https://assets.imgix.net/examples/pione.jpg" sizes="100vw" imgixParams={{ fit: "crop" }} /> `
The other major change relates to how the component determines an image's aspect ratio. Instead of appending a calculated height
h= value based on specified dimensions, the URL string will now be built using the imgix aspect ratio parameterar=. Luckily, the interface for specifying an aspect ratio is no different from before. However, users will have to pass in the fit=crop parameter in order for it to take effect:`jsx src="http://assets.imgix.net/examples/pione.jpg" width={400} imgixParams={{ ar: "2:1", fit: "crop" }} /> `
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This is a very large update to this library with a lot of breaking changes. We apologise for any issues this may cause, and we have tried to reduce the number of breaking changes. We have also worked to batch up all these changes into one release to reduce its impacts. We do not plan on making breaking changes for a while after this, and will be focussed on adding features.
The largest change in this major version bump is the move to width-based
srcSet and sizes for responsiveness. This has a host of benefits, including better server rendering, better responsiveness, less potential for bugs, and performance improvements. This does mean that the old fitting-to-container-size behaviour has been removed. If this is necessary, an example of how this can be achieved can be found here
To upgrade to version 8, the following changes should be made.
- A
sizes prop should be added to all usages of . If sizes is new to you (or even if it's not), Eric's seminal article on srcset and sizes is highly recommended. - Change all usages of type='picture' to and type='source' to
type='bg' as it is no longer supported. It was decided that it was too hard to implement this feature consistently. If you would still like to use this feature, please give this issue a thumbs up: https://github.com/imgix/react-imgix/issues/160 If we get enough requests for this, we will re-implement it. - Remove props aggressiveLoad, component, fluid, precision as they are no longer used. - Change all usages of defaultHeight and defaultWidth to width and height props. - Rename generateSrcSet to disableSrcSet and invert the value passed down as the prop's value. i.e. generateSrcSet={false} becomes disableSrcSet={true} or simply disableSrcSet - If support is needed for a browser which does not support the new usage of srcSet (such as IE 11), we recommended adding a polyfill, such as the great Picturefill.
Browser Support
- By default, browsers that don't support
srcset, sizes, or picture will gracefully fall back to the default imgsrc` when appropriate. If you want to provide a fully-responsive experience for these browsers, react-imgix works great alongside Picturefill! - We support the latest version of Google Chrome (which automatically updates whenever it detects that a new version of the browser is available). We also support the current and previous major releases of desktop Firefox, Internet Explorer, and Safari on a rolling basis. Mobile support is tested on the most recent minor version of the current and previous major release for the default browser on iOS and Android (e.g., iOS 9.2 and 8.4). Each time a new version is released, we begin supporting that version and stop supporting the third most recent version.
This browser support is made possible by the great support from BrowserStack.
Contributors
Thanks goes to these wonderful people (emoji key):
This project follows the all-contributors specification. Contributions of any kind welcome, but please review the contribution guidelines before getting started!
Meta
React-imgix was originally created by Frederick Fogerty. It's licensed under the ISC license (see the license file for more info).
