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fix(compat): avoid mutating user-provided style objects when appending px #5117

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fix(compat): avoid mutating user-provided style objects when appending px #5117

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19d104d
fix(compat): avoid mutating user-provided style objects when appendin…
JSap0914 Jun 17, 2026
ef09510
address review: clone style lazily only when appending px
JSap0914 Jun 17, 2026
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5 changes: 5 additions & 0 deletions compat/src/render.js
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Original file line number Diff line number Diff line change
Expand Up @@ -136,8 +136,13 @@ function handleDomVNode(vnode) {
}

if (i === 'style' && typeof value === 'object') {
let cloned = false;

@JoviDeCroock JoviDeCroock Jul 16, 2026

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Suggested change
let cloned = false;
let cloned;

for (let key in value) {
if (typeof value[key] === 'number' && !IS_NON_DIMENSIONAL.test(key)) {
if (!cloned) {
value = assign({}, value);
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cloned = true;
Comment on lines +143 to +144

@JoviDeCroock JoviDeCroock Jul 16, 2026

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Suggested change
value = assign({}, value);
cloned = true;
cloned = value = assign({}, value);

}
value[key] += 'px';
}
}
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7 changes: 7 additions & 0 deletions compat/test/browser/render.test.jsx
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Expand Up @@ -886,4 +886,11 @@ describe('compat render', () => {
}
}
});

it('should not mutate the original style object when appending px', () => {
const style = { margin: 10, opacity: 0.5 };
render(<div style={style} />, scratch);

expect(style).to.deep.equal({ margin: 10, opacity: 0.5 });
});
});