perf: micro-optimizations in hot paths#2960
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jasonlyu123 merged 6 commits intosveltejs:masterfrom Mar 14, 2026
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…gnostics Replace O(n²) flatten() with Array.prototype.flat(), remove lodash flatten dependency from PluginHost, use Object.create instead of object spread in svelteNodeAt AST walking, cache getExistingImports per document, use RegExp.test() over .match(), replace regex with charCode check in possiblyComponent, use cached line offsets for lineCount, and optimize iteration in SnapshotManager. Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
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Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
jasonlyu123
requested changes
Mar 2, 2026
packages/language-server/src/plugins/typescript/SnapshotManager.ts
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packages/language-server/src/plugins/typescript/features/CompletionProvider.ts
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- Replace all flatten() call sites with .flat()/.flatMap() and remove the flatten utility function entirely - Use charCodeAt(0) directly in possiblyComponent instead of char comparison - Use block syntax for single-line for loops in SnapshotManager - Remove ineffective existingImportsCache from CompletionProvider Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
jasonlyu123
approved these changes
Mar 12, 2026
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Summary
flatten()withArray.prototype.flat()— the existing reduce+spread implementation copies the accumulator on every iteration. Called from DiagnosticsProvider, CompletionProvider, FindReferencesProvider, CodeActionsProvider, and moreflattenfrom PluginHost — replaces ~10flatten(...)call sites with.flat(). PluginHost is the central dispatch for all LSP operationsObject.create(node)instead of{ ...node }insvelteNodeAt— avoids copying all AST node properties on every matching ancestor while walking the tree. Called from completions, diagnostics, rename, and semantic tokensgetExistingImportsper document URI + version — avoids re-parsing all imports via regex on every completion requestRegExp.test()inisExistingSvelteComponentImport— avoids allocating a match array for every Svelte component completion itempossiblyComponentregex with charCode comparison — regex is overkill for checking a single ASCII uppercase characterlineCountto use cached line offsets — was splitting the entire document text on every call whengetLineOffsets()is already cachedgetByPrefixto iterate without intermediate array — push loop instead ofArray.from+ filter + map chainlogStatisticsto single-pass counting — replaces Set→Array conversion and double.filter()with a single loopTest plan
pnpm build🤖 Generated with Claude Code