perf: replace startsWith with strict equality (#6094)

btea · web-flow · commit 235dc74fbe75 · 2025-09-07T07:47:04.000+02:00
diff --git a/docs/.vitepress/verify-anchors.ts b/docs/.vitepress/verify-anchors.ts
@@ -40,7 +40,7 @@ function verifyAnchorsOnPage(page: string, slugs: Set<string>) {
 	let match: (RegExpExecArray & { groups?: { href?: string } }) | null;
 	while ((match = markdownLinkRegExp.exec(text)) !== null) {
 		const [href] = match;
-		if (href.startsWith('#')) {
+		if (href[0] === '#') {
 			const anchor = href.slice(1);
 			if (!slugs.has(anchor)) {
 				console.log(slugs);
diff --git a/docs/repl/helpers/query.ts b/docs/repl/helpers/query.ts
@@ -16,7 +16,7 @@ export async function useUpdateStoresFromQuery() {
 	try {
 		if (query.shareable) {
 			const rawJson = atob(query.shareable.replace(/_/g, '/').replace(/-/g, '+'));
-			const json = rawJson.startsWith('%') ? decodeURIComponent(rawJson) : rawJson;
+			const json = rawJson[0] === '%' ? decodeURIComponent(rawJson) : rawJson;
 			const {
 				modules: queryModules,
 				options: queryOptions,
diff --git a/scripts/test-options.js b/scripts/test-options.js
@@ -73,7 +73,7 @@ for (const line of splitHelpText) {
 	}
 }
 
-const helpOptionLines = splitHelpText.filter(line => line.startsWith('-'));
+const helpOptionLines = splitHelpText.filter(line => line[0] === '-');
 
 const cliFlagsText = commandReferenceText
 	.split('\n## ')
@@ -85,7 +85,7 @@ const cliMarkdownSection = cliFlagsText.match(/```\n([\S\s]*?)\n```/);
 if (!cliMarkdownSection) {
 	throw new Error('Could not find markdown section in "Command line flags" section.');
 }
-const optionListLines = cliMarkdownSection[1].split('\n').filter(line => line.startsWith('-'));
+const optionListLines = cliMarkdownSection[1].split('\n').filter(line => line[0] === '-');
 
 for (const [index, line] of helpOptionLines.entries()) {
 	const optionListLine = optionListLines[index];
diff --git a/src/Chunk.ts b/src/Chunk.ts
@@ -966,7 +966,7 @@ export default class Chunk {
 							variable.isNamespace &&
 							namespaceInteropHelpersByInteropType[interop(module.id)] &&
 							(this.imports.has(variable) ||
-								!this.exportNamesByVariable.get(variable)?.every(name => name.startsWith('*')))
+								!this.exportNamesByVariable.get(variable)?.every(name => name[0] === '*'))
 						) {
 							// We only need to deconflict it if the namespace is actually
 							// created as a variable, i.e. because it is used internally or
@@ -1143,7 +1143,7 @@ export default class Chunk {
 				return idWithoutExtension.slice(preserveModulesRoot.length).replace(/^[/\\]/, '');
 			} else {
 				// handle edge case in Windows
-				if (this.inputBase === '/' && !idWithoutExtension.startsWith('/')) {
+				if (this.inputBase === '/' && idWithoutExtension[0] !== '/') {
 					return relative(this.inputBase, idWithoutExtension.replace(/^[a-zA-Z]:[/\\]/, '/'));
 				}
 				return relative(this.inputBase, idWithoutExtension);
diff --git a/src/utils/getLogFilter.ts b/src/utils/getLogFilter.ts
@@ -5,7 +5,7 @@ export const getLogFilter: GetLogFilter = filters => {
 	if (filters.length === 0) return () => true;
 	const normalizedFilters = filters.map(filter =>
 		filter.split('&').map(subFilter => {
-			const inverted = subFilter.startsWith('!');
+			const inverted = subFilter[0] === '!';
 			if (inverted) subFilter = subFilter.slice(1);
 			const [key, ...value] = subFilter.split(':');
 			return { inverted, key: key.split('.'), parts: value.join(':').split('*') };
diff --git a/src/utils/options/normalizeInputOptions.ts b/src/utils/options/normalizeInputOptions.ts
@@ -97,7 +97,7 @@ const getIdMatcher = <T extends any[]>(
 		return () => true;
 	}
 	if (typeof option === 'function') {
-		return (id, ...parameters) => (!id.startsWith('\0') && option(id, ...parameters)) || false;
+		return (id, ...parameters) => (id[0] !== '\0' && option(id, ...parameters)) || false;
 	}
 	if (option) {
 		const ids = new Set<string>();
@@ -241,7 +241,7 @@ const getHasModuleSideEffects = (
 	}
 	if (typeof moduleSideEffectsOption === 'function') {
 		return (id, external) =>
-			id.startsWith('\0') ? true : moduleSideEffectsOption(id, external) !== false;
+			id[0] === '\0' ? true : moduleSideEffectsOption(id, external) !== false;
 	}
 	if (Array.isArray(moduleSideEffectsOption)) {
 		const ids = new Set(moduleSideEffectsOption);
diff --git a/test/function/samples/external-ignore-reserved-null-marker/_config.js b/test/function/samples/external-ignore-reserved-null-marker/_config.js
@@ -2,7 +2,7 @@ module.exports = defineTest({
 	description: 'external function ignores \\0 started ids',
 	options: {
 		external(id) {
-			if (id.startsWith('\0')) {
+			if (id[0] === '\0') {
 				throw new Error('\\0 started ids should not be tested as external');
 			}
 			return true;
diff --git a/test/testHelpers.js b/test/testHelpers.js
@@ -497,7 +497,7 @@ const replaceStringifyValues = (key, value) => {
 		}
 	}
 
-	return key.startsWith('_')
+	return key[0] === '_'
 		? undefined
 		: typeof value == 'bigint'
 			? `~BigInt${value.toString()}`

Original file line number	Diff line number	Diff line change
`@@ -73,7 +73,7 @@ for (const line of splitHelpText) {`
`73`	`73`	`}`
`74`	`74`	`}`
`75`	`75`
`76`		`-const helpOptionLines = splitHelpText.filter(line => line.startsWith('-'));`
	`76`	`+const helpOptionLines = splitHelpText.filter(line => line[0] === '-');`
`77`	`77`
`78`	`78`	`const cliFlagsText = commandReferenceText`
`79`	`79`	`.split('\n## ')`
@@ -85,7 +85,7 @@ const cliMarkdownSection = cliFlagsText.match(/```\n([\S\s]*?)\n```/);
`85`	`85`	`if (!cliMarkdownSection) {`
`86`	`86`	`throw new Error('Could not find markdown section in "Command line flags" section.');`
`87`	`87`	`}`
`88`		`-const optionListLines = cliMarkdownSection[1].split('\n').filter(line => line.startsWith('-'));`
	`88`	`+const optionListLines = cliMarkdownSection[1].split('\n').filter(line => line[0] === '-');`
`89`	`89`
`90`	`90`	`for (const [index, line] of helpOptionLines.entries()) {`
`91`	`91`	`const optionListLine = optionListLines[index];`
Original file line number	Diff line number	Diff line change
`@@ -97,7 +97,7 @@ const getIdMatcher = <T extends any[]>(`
`97`	`97`	`return () => true;`
`98`	`98`	`}`
`99`	`99`	`if (typeof option === 'function') {`
`100`		`- return (id, ...parameters) => (!id.startsWith('\0') && option(id, ...parameters)) \|\| false;`
	`100`	`+ return (id, ...parameters) => (id[0] !== '\0' && option(id, ...parameters)) \|\| false;`
`101`	`101`	`}`
`102`	`102`	`if (option) {`
`103`	`103`	`const ids = new Set<string>();`
`@@ -241,7 +241,7 @@ const getHasModuleSideEffects = (`
`241`	`241`	`}`
`242`	`242`	`if (typeof moduleSideEffectsOption === 'function') {`
`243`	`243`	`return (id, external) =>`
`244`		`- id.startsWith('\0') ? true : moduleSideEffectsOption(id, external) !== false;`
	`244`	`+ id[0] === '\0' ? true : moduleSideEffectsOption(id, external) !== false;`
`245`	`245`	`}`
`246`	`246`	`if (Array.isArray(moduleSideEffectsOption)) {`
`247`	`247`	`const ids = new Set(moduleSideEffectsOption);`
Original file line number	Diff line number	Diff line change
`@@ -2,7 +2,7 @@ module.exports = defineTest({`
`2`	`2`	`description: 'external function ignores \\0 started ids',`
`3`	`3`	`options: {`
`4`	`4`	`external(id) {`
`5`		`- if (id.startsWith('\0')) {`
	`5`	`+ if (id[0] === '\0') {`
`6`	`6`	`throw new Error('\\0 started ids should not be tested as external');`
`7`	`7`	`}`
`8`	`8`	`return true;`
Original file line number	Diff line number	Diff line change
`@@ -497,7 +497,7 @@ const replaceStringifyValues = (key, value) => {`
`497`	`497`	`}`
`498`	`498`	`}`
`499`	`499`
`500`		`- return key.startsWith('_')`
	`500`	`+ return key[0] === '_'`
`501`	`501`	`? undefined`
`502`	`502`	`: typeof value == 'bigint'`
`503`	`503`	? `~BigInt${value.toString()}`