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fix(vite): keep value: undefined in HMR-served Vue scripts #11542

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Merged
NathanWalker merged 2 commits into from
Oct 21, 2026
Merged

fix(vite): keep value: undefined in HMR-served Vue scripts #11542

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235ebb4
fix(vite): keep `value: undefined` in HMR-served Vue scripts
triniwiz Oct 15, 2026
3e306eb
chore(vite): drop comments
triniwiz Oct 15, 2026
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23 changes: 23 additions & 0 deletions packages/vite/hmr/helpers/ast-extract.spec.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -31,4 +31,27 @@ export default obj;
expect(result.diagnostics.some((d) => d.includes('[ast][warn]'))).toBe(false);
expect(result.body.replace(/\s+/g, ' ').trim()).toContain('const obj = { default: 1, other: 2 }');
});

it('keeps object properties whose value is undefined or null', () => {
const source = `
import { ref } from 'vue';
const themeOptions = [{ label: 'System', value: undefined }, { label: 'Light', value: 'light' }];
const flags = { a: 1, b: null, c: void 0, nullable: 2 };
`;
const body = astExtractImportsAndStripTypes(source).body.replace(/\s+/g, ' ');
expect(body).toContain("{ label: 'System', value: undefined }");
expect(body).toContain('{ a: 1, b: null, c: void 0, nullable: 2 }');
});

it('strips type annotations left on function parameters', () => {
const source = `
function f(a: string, b?: undefined, ...rest: any[]) { return [a, b, rest]; }
const g = (x: number = 1) => x;
`;
const result = astExtractImportsAndStripTypes(source);
const body = result.body.replace(/\s+/g, ' ');
expect(body).toContain('function f(a, b, ...rest)');
expect(body).toContain('const g = (x = 1) => x');
expect(result.diagnostics).toEqual(expect.arrayContaining(['[ast-fallback] stripped residual param annotations']));
});
});
37 changes: 32 additions & 5 deletions packages/vite/hmr/helpers/ast-extract.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -8,6 +8,34 @@ export interface AstProcessResult {
diagnostics: string[];
}

function stripParamAnnotations(statements: Statement[]): boolean {
let stripped = false;
const strip = (param: any) => {
for (const node of [param, param?.left, param?.argument, param?.parameter]) {
if (node?.typeAnnotation) {
node.typeAnnotation = null;
stripped = true;
}
if (node?.optional) {
node.optional = false;
stripped = true;
}
}
};
const visit = (node: any) => {
if (!node || typeof node.type !== 'string') return;
if (Array.isArray(node.params)) node.params.forEach(strip);
for (const key of Object.keys(node)) {
if (key === 'loc' || key === 'leadingComments' || key === 'trailingComments' || key === 'innerComments') continue;
const value = node[key];
if (Array.isArray(value)) value.forEach(visit);
else if (value && typeof value === 'object') visit(value);
}
};
statements.forEach(visit);
return stripped;
}

export function astExtractImportsAndStripTypes(source: string): AstProcessResult {
const diagnostics: string[] = [];
let ast: File | null = null;
Expand Down Expand Up @@ -39,6 +67,10 @@ export function astExtractImportsAndStripTypes(source: string): AstProcessResult
}
}

if (stripParamAnnotations(other)) {
diagnostics.push('[ast-fallback] stripped residual param annotations');
}

const fileNoImports: File = {
...ast,
program: { ...ast.program, body: other },
Expand All @@ -52,11 +84,6 @@ export function astExtractImportsAndStripTypes(source: string): AstProcessResult
bodyCode = source;
}

if (/(\(|,|=)\s*[A-Za-z_$][\w$]*\s*:\s*(?:boolean|string|number|any|unknown|void|null|undefined)/.test(bodyCode)) {
bodyCode = bodyCode.replace(/(\(|,|=)\s*([A-Za-z_$][\w$]*)\s*:\s*(boolean|string|number|any|unknown|void|null|undefined)/g, '$1 $2');
diagnostics.push('[ast-fallback] stripped residual param annotations');
}

const beforeVarStrip = bodyCode;
bodyCode = bodyCode.replace(/\b(const|let|var)\s+([A-Za-z_$][\w$]*)\s*:\s*([^=;]+?)(=)/g, (_m, decl, name, _type, eq) => `${decl} ${name} ${eq}`);
if (bodyCode !== beforeVarStrip) {
Expand Down
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