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Warn when "false" or "true" is the value of a boolean DOM prop #13372

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merged 4 commits into from
Aug 14, 2018
Merged

Warn when "false" or "true" is the value of a boolean DOM prop #13372

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1447508
Warn when the string "false" is the value of a boolean DOM prop
motiz88 Aug 11, 2018
b8f83cd
Only warn on exact case match for "false" in DOM boolean props
motiz88 Aug 12, 2018
f3248f2
Warn on string "true" as well as "false" in DOM boolean props
motiz88 Aug 12, 2018
f70a0eb
Clarify warnings on "true" / "false" values in DOM boolean props
motiz88 Aug 12, 2018
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28 changes: 28 additions & 0 deletions packages/react-dom/src/__tests__/ReactDOMComponent-test.js
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Original file line number Diff line number Diff line change
Expand Up @@ -2506,6 +2506,34 @@ describe('ReactDOMComponent', () => {
});
});

describe('Boolean attributes', function() {
it('warns on the ambiguous string value "false"', function() {
let el;
expect(() => {
el = ReactTestUtils.renderIntoDocument(<div hidden="false" />);
}).toWarnDev(
'Received the string `false` for the boolean attribute `hidden`. ' +
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'The browser will interpret it as a truthy value. ' +
'Did you mean hidden={false}?',
);

expect(el.getAttribute('hidden')).toBe('');
});

it('warns on the potentially-ambiguous string value "true"', function() {
let el;
expect(() => {
el = ReactTestUtils.renderIntoDocument(<div hidden="true" />);
}).toWarnDev(
'Received the string `true` for the boolean attribute `hidden`. ' +
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Maybe add Although this works, it will not work as expected if you pass the string "false". to the true case.

'Although this works, it will not work as expected if you pass the string "false". ' +
'Did you mean hidden={true}?',
);

expect(el.getAttribute('hidden')).toBe('');
});
});

describe('Hyphenated SVG elements', function() {
it('the font-face element is not a custom element', function() {
let el;
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2 changes: 1 addition & 1 deletion packages/react-dom/src/__tests__/ReactDOMInput-test.js
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Expand Up @@ -444,7 +444,7 @@ describe('ReactDOMInput', () => {

it('should take `defaultValue` when changing to uncontrolled input', () => {
const node = ReactDOM.render(
<input type="text" value="0" readOnly="true" />,
<input type="text" value="0" readOnly={true} />,
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This test was broken by adding the warning on "true". I opted to just fix what the warning was complaining about, which doesn't change the semantics of this test AFAICT.

container,
);
expect(node.value).toBe('0');
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24 changes: 24 additions & 0 deletions packages/react-dom/src/shared/ReactDOMUnknownPropertyHook.js
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Original file line number Diff line number Diff line change
Expand Up @@ -13,6 +13,7 @@ import warning from 'shared/warning';

import {
ATTRIBUTE_NAME_CHAR,
BOOLEAN,
RESERVED,
shouldRemoveAttributeWithWarning,
getPropertyInfo,
Expand Down Expand Up @@ -226,6 +227,29 @@ if (__DEV__) {
return false;
}

// Warn when passing the strings 'false' or 'true' into a boolean prop
if (
(value === 'false' || value === 'true') &&
propertyInfo !== null &&
propertyInfo.type === BOOLEAN
) {
warning(
false,
'Received the string `%s` for the boolean attribute `%s`. ' +
'%s ' +
'Did you mean %s={%s}?',
value,
name,
value === 'false'
? 'The browser will interpret it as a truthy value.'
: 'Although this works, it will not work as expected if you pass the string "false".',
name,
value,
);
warnedProperties[name] = true;
return true;
}

return true;
};
}
Expand Down