'use strict';
describe('ReactDOM unknown attribute', () => {
let React;
let ReactDOMClient;
let act;
let assertConsoleErrorDev;
beforeEach(() => {
jest.resetModules();
React = require('react');
ReactDOMClient = require('react-dom/client');
act = require('internal-test-utils').act;
assertConsoleErrorDev =
require('internal-test-utils').assertConsoleErrorDev;
});
async function testUnknownAttributeRemoval(givenValue) {
const el = document.createElement('div');
const root = ReactDOMClient.createRoot(el);
await act(() => {
root.render(<div unknown="something" />);
});
expect(el.firstChild.getAttribute('unknown')).toBe('something');
await act(() => {
root.render(<div unknown={givenValue} />);
});
expect(el.firstChild.hasAttribute('unknown')).toBe(false);
}
async function testUnknownAttributeAssignment(givenValue, expectedDOMValue) {
const el = document.createElement('div');
const root = ReactDOMClient.createRoot(el);
await act(() => {
root.render(<div unknown="something" />);
});
expect(el.firstChild.getAttribute('unknown')).toBe('something');
await act(() => {
root.render(<div unknown={givenValue} />);
});
expect(el.firstChild.getAttribute('unknown')).toBe(expectedDOMValue);
}
describe('unknown attributes', () => {
it('removes values null and undefined', async () => {
await testUnknownAttributeRemoval(null);
await testUnknownAttributeRemoval(undefined);
});
it('changes values true, false to null, and also warns once', async () => {
await testUnknownAttributeAssignment(true, null);
assertConsoleErrorDev([
'Received `true` for a non-boolean attribute `unknown`.\n\n' +
'If you want to write it to the DOM, pass a string instead: ' +
'unknown="true" or unknown={value.toString()}.\n' +
' in div (at **)',
]);
await testUnknownAttributeAssignment(false, null);
});
it('removes unknown attributes that were rendered but are now missing', async () => {
const el = document.createElement('div');
const root = ReactDOMClient.createRoot(el);
await act(() => {
root.render(<div unknown="something" />);
});
expect(el.firstChild.getAttribute('unknown')).toBe('something');
await act(() => {
root.render(<div />);
});
expect(el.firstChild.hasAttribute('unknown')).toBe(false);
});
it('removes new boolean props', async () => {
const el = document.createElement('div');
const root = ReactDOMClient.createRoot(el);
await act(() => {
root.render(<div inert={true} />);
});
expect(el.firstChild.getAttribute('inert')).toBe(true ? '' : null);
});
it('warns once for empty strings in new boolean props', async () => {
const el = document.createElement('div');
const root = ReactDOMClient.createRoot(el);
await act(() => {
root.render(<div inert="" />);
});
assertConsoleErrorDev([
'Received an empty string for a boolean attribute `inert`. ' +
'This will treat the attribute as if it were false. ' +
'Either pass `false` to silence this warning, or ' +
'pass `true` if you used an empty string in earlier versions of React to indicate this attribute is true.\n' +
' in div (at **)',
]);
expect(el.firstChild.getAttribute('inert')).toBe(true ? null : '');
await act(() => {
root.render(<div inert="" />);
});
});
it('passes through strings', async () => {
await testUnknownAttributeAssignment('a string', 'a string');
});
it('coerces numbers to strings', async () => {
await testUnknownAttributeAssignment(0, '0');
await testUnknownAttributeAssignment(-1, '-1');
await testUnknownAttributeAssignment(42, '42');
await testUnknownAttributeAssignment(9000.99, '9000.99');
});
it('coerces NaN to strings and warns', async () => {
await testUnknownAttributeAssignment(NaN, 'NaN');
assertConsoleErrorDev([
'Received NaN for the `unknown` attribute. ' +
'If this is expected, cast the value to a string.\n' +
' in div (at **)',
]);
});
it('coerces objects to strings and warns', async () => {
const lol = {
toString() {
return 'lol';
},
};
await testUnknownAttributeAssignment({hello: 'world'}, '[object Object]');
await testUnknownAttributeAssignment(lol, 'lol');
});
it('throws with Temporal-like objects', async () => {
class TemporalLike {
valueOf() {
throw new TypeError('prod message');
}
toString() {
return '2020-01-01';
}
}
const test = () =>
testUnknownAttributeAssignment(new TemporalLike(), null);
await expect(test).rejects.toThrowError(new TypeError('prod message'));
assertConsoleErrorDev([
'The provided `unknown` attribute is an unsupported type TemporalLike.' +
' This value must be coerced to a string before using it here.\n' +
' in div (at **)',
]);
});
it('removes symbols and warns', async () => {
await testUnknownAttributeRemoval(Symbol('foo'));
assertConsoleErrorDev([
'Invalid value for prop `unknown` on <div> tag. Either remove it ' +
'from the element, or pass a string or number value to keep it ' +
'in the DOM. For details, see https://react.dev/link/attribute-behavior \n' +
' in div (at **)',
]);
});
it('removes functions and warns', async () => {
await testUnknownAttributeRemoval(function someFunction() {});
assertConsoleErrorDev([
'Invalid value for prop `unknown` on <div> tag. Either remove ' +
'it from the element, or pass a string or number value to ' +
'keep it in the DOM. For details, see ' +
'https://react.dev/link/attribute-behavior \n' +
' in div (at **)',
]);
});
it('allows camelCase unknown attributes and warns', async () => {
const el = document.createElement('div');
const root = ReactDOMClient.createRoot(el);
await act(() => {
root.render(<div helloWorld="something" />);
});
assertConsoleErrorDev([
'React does not recognize the `helloWorld` prop on a DOM element. ' +
'If you intentionally want it to appear in the DOM as a custom ' +
'attribute, spell it as lowercase `helloworld` instead. ' +
'If you accidentally passed it from a parent component, remove ' +
'it from the DOM element.\n' +
' in div (at **)',
]);
expect(el.firstChild.getAttribute('helloworld')).toBe('something');
});
});
});