Since React 16 now allows custom DOM attributes, I tried to leverage this in my Typescript code:
import * as React from 'react';
<div className="page" size="A4">
</div>
but receive this error message:
error TS2339: Property 'size' does not exist on type 'DetailedHTMLProps< HTMLAttributes< HTMLDivElement>, HTMLDivElement>'.
This thread suggests to do a module augmentation, so I tried this way:
import * as React from 'react';
declare module 'react' {
interface HTMLProps<T> {
size?:string;
}
}
Same error message.
Finally, I also tried to declare page as a new HTML tag:
declare global {
namespace JSX {
interface IntrinsicElements {
page: any
}
}
}
<page className="page" size="A4">
</page>
It gets rid of the error message, but the size attribute is completely ignored in the compiled code, and I end up with:
<page className="page">
</page>
Ideally, the last one is my preferred solution. I'd like to use the size custom attribute alongside the page custom tag.
tsconfig.js
{
"compilerOptions": {
"outDir": "build/dist",
"module": "esnext",
"target": "es5",
"lib": ["es6", "dom"],
"sourceMap": true,
"allowJs": true,
"jsx": "react",
"moduleResolution": "node",
"rootDir": "src",
"forceConsistentCasingInFileNames": true,
"noImplicitReturns": true,
"noImplicitThis": true,
"noImplicitAny": true,
"strictNullChecks": true,
"suppressImplicitAnyIndexErrors": true,
"allowSyntheticDefaultImports": true,
"noUnusedLocals": false,
"noUnusedParameters": false,
"allowUnusedLabels": true,
"allowUnreachableCode": true
}
}
HTML supports data-* attribute type for custom attributes. You can read about it more here.
Definition and Usage The data-* attributes is used to store custom data private to the page or application.
The data-* attributes gives us the ability to embed custom data attributes on all HTML elements.
The stored (custom) data can then be used in the page's JavaScript to create a more engaging user experience (without any Ajax calls or server-side database queries).
The data-* attributes consist of two parts:
- The attribute name should not contain any uppercase letters, and must be at least one character long after the prefix "data-"
- The attribute value can be any string
Note: Custom attributes prefixed with "data-" will be completely ignored by the user agent.
Rather than just using size="A4" you can use data-size="A4"
Example
<div className="page" data-size="A4">
// ....
</div>
React type definition file (by default - index.d.ts when staring with create-react-app) contain list of all the standard HTML elements, as well as known attributes.
In order to allow custom HTML attributes, you need to define it's typing.
Do that by expanding HTMLAttributes interface:
declare module 'react' {
interface HTMLAttributes<T> extends AriaAttributes, DOMAttributes<T> {
// extends React's HTMLAttributes
custom?: string;
}
}
Possibly related question:
How do I add attributes to existing HTML elements in TypeScript/JSX?
If you are using styled-components, you can do it even simplier:
const App = props => {
return <StyledDiv version={2.0}>My custom div</StyledDiv>
}
type Custom = {
version?: number
}
const StyledDiv = styled.div<Custom>`
// styles
`