⚡ Bolt: [performance improvement] Replace querySelectorAll(...)[0] with querySelector#123
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…th querySelector Co-authored-by: bartholomej <5861310+bartholomej@users.noreply.github.com>
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📝 WalkthroughWalkthroughReplaces inefficient DOM queries in two helper files (uses Changes
Estimated code review effort🎯 3 (Moderate) | ⏱️ ~20 minutes Possibly related PRs
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Actionable comments posted: 1
🤖 Prompt for all review comments with AI agents
Verify each finding against the current code and only fix it if needed.
Inline comments:
In `@src/helpers/search.helper.ts`:
- Around line 18-21: In getSearchYear, calling .replace() on the result of
?.innerText can throw if innerText is undefined; update the expression to use
optional chaining before replace and provide a safe fallback so the unary +
won't throw — e.g. change the return to use el.querySelector('.film-title-info
.info')?.innerText?.replace(/[{()}]/g, '') ?? '' (or otherwise default to an
empty string) before coercing to a number; this fixes the runtime TypeError in
getSearchYear when the queried node is missing.
ℹ️ Review info
⚙️ Run configuration
Configuration used: defaults
Review profile: CHILL
Plan: Pro
Run ID: 6fe0b6e8-6228-4f03-9d4c-f250d9ce270d
📒 Files selected for processing (2)
src/helpers/creator.helper.tssrc/helpers/search.helper.ts
| export const getSearchYear = (el: HTMLElement): number => { | ||
| return +el.querySelectorAll('.film-title-info .info')[0]?.innerText.replace(/[{()}]/g, ''); | ||
| // ⚡ Bolt: Use querySelector instead of querySelectorAll(...)[0] to prevent unnecessary DOM traversal | ||
| return +el.querySelector('.film-title-info .info')?.innerText.replace(/[{()}]/g, ''); | ||
| }; |
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Missing optional chaining before .replace() can cause runtime error.
If querySelector returns null (element not found), ?.innerText evaluates to undefined, and calling .replace() on undefined throws a TypeError. Add optional chaining before .replace():
export const getSearchYear = (el: HTMLElement): number => {
// ⚡ Bolt: Use querySelector instead of querySelectorAll(...)[0] to prevent unnecessary DOM traversal
- return +el.querySelector('.film-title-info .info')?.innerText.replace(/[{()}]/g, '');
+ return +el.querySelector('.film-title-info .info')?.innerText?.replace(/[{()}]/g, '');
};Based on learnings: "Never assume an element exists. CSFD changes layouts. Use optional chaining ?. or try/catch inside helpers for robust scraping."
📝 Committable suggestion
‼️ IMPORTANT
Carefully review the code before committing. Ensure that it accurately replaces the highlighted code, contains no missing lines, and has no issues with indentation. Thoroughly test & benchmark the code to ensure it meets the requirements.
| export const getSearchYear = (el: HTMLElement): number => { | |
| return +el.querySelectorAll('.film-title-info .info')[0]?.innerText.replace(/[{()}]/g, ''); | |
| // ⚡ Bolt: Use querySelector instead of querySelectorAll(...)[0] to prevent unnecessary DOM traversal | |
| return +el.querySelector('.film-title-info .info')?.innerText.replace(/[{()}]/g, ''); | |
| }; | |
| export const getSearchYear = (el: HTMLElement): number => { | |
| // ⚡ Bolt: Use querySelector instead of querySelectorAll(...)[0] to prevent unnecessary DOM traversal | |
| return +el.querySelector('.film-title-info .info')?.innerText?.replace(/[{()}]/g, ''); | |
| }; |
🤖 Prompt for AI Agents
Verify each finding against the current code and only fix it if needed.
In `@src/helpers/search.helper.ts` around lines 18 - 21, In getSearchYear, calling
.replace() on the result of ?.innerText can throw if innerText is undefined;
update the expression to use optional chaining before replace and provide a safe
fallback so the unary + won't throw — e.g. change the return to use
el.querySelector('.film-title-info .info')?.innerText?.replace(/[{()}]/g, '') ??
'' (or otherwise default to an empty string) before coercing to a number; this
fixes the runtime TypeError in getSearchYear when the queried node is missing.
…SelectorAll(...)[0] Co-authored-by: bartholomej <5861310+bartholomej@users.noreply.github.com>
Codecov Report✅ All modified and coverable lines are covered by tests. Additional details and impacted files@@ Coverage Diff @@
## master #123 +/- ##
=======================================
Coverage 99.46% 99.46%
=======================================
Files 34 34
Lines 746 746
Branches 181 181
=======================================
Hits 742 742
Misses 4 4 ☔ View full report in Codecov by Sentry. 🚀 New features to boost your workflow:
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🧹 Nitpick comments (2)
src/fetchers/index.ts (2)
4-7: Rotate theUser-AgentinsidefetchPage.Updating the strings here helps, but Line 11 still picks one value at module load, so every later request reuses the same
User-Agent. If the goal is to vary the request fingerprint, move the selection intofetchPage.♻️ Suggested refactor
-const defaultHeaders = { - 'User-Agent': USER_AGENTS[Math.floor(Math.random() * USER_AGENTS.length)], +const createDefaultHeaders = (): HeadersInit => ({ + 'User-Agent': USER_AGENTS[Math.floor(Math.random() * USER_AGENTS.length)], 'Accept': 'text/html,application/xhtml+xml,application/xml;q=0.9,image/avif,image/webp,image/apng,*/*;q=0.8,application/signed-exchange;v=b3;q=0.7', 'Accept-Language': 'cs,en;q=0.9,en-US;q=0.8', 'Upgrade-Insecure-Requests': '1', 'Sec-Fetch-Dest': 'document', 'Sec-Fetch-Mode': 'navigate', 'Sec-Fetch-Site': 'none', 'Sec-Fetch-User': '?1' -}; +}); export const fetchPage = async (url: string, optionsRequest?: RequestInit): Promise<string> => { try { - const mergedHeaders = new Headers(defaultHeaders); + const mergedHeaders = new Headers(createDefaultHeaders());🤖 Prompt for AI Agents
Verify each finding against the current code and only fix it if needed. In `@src/fetchers/index.ts` around lines 4 - 7, The file currently picks a single User-Agent at module load and reuses it for all requests; change this by moving the random selection into the fetchPage function so a new User-Agent is chosen per call. Inside fetchPage, import or reference the user agents array (e.g., userAgents or USER_AGENTS) and compute a random index / pick a random element on each invocation, then set/merge that value into the request headers before performing the fetch; ensure any existing header-merge logic preserves other headers and that tests/consumers of fetchPage continue to receive the updated headers per request.
12-18: Add a focused test for the new default headers.This changes the outbound request fingerprint, but the current custom-header test only checks the response body. A regression in these defaults or in header override precedence would still pass, so please add an assertion around the headers passed to
fetchSafe.🤖 Prompt for AI Agents
Verify each finding against the current code and only fix it if needed. In `@src/fetchers/index.ts` around lines 12 - 18, The test suite needs an explicit assertion that the default outbound headers and override precedence are passed into fetchSafe: update the existing custom-header test to spy/mock fetchSafe (the fetchSafe function exported from the fetchers module) and capture the request init->headers, then assert the presence and exact values of the default headers (e.g., Accept, Accept-Language, Upgrade-Insecure-Requests, Sec-Fetch-*) and also assert that when custom headers are provided they override the defaults; ensure the test fails if defaults change or override precedence is wrong.
🤖 Prompt for all review comments with AI agents
Verify each finding against the current code and only fix it if needed.
Nitpick comments:
In `@src/fetchers/index.ts`:
- Around line 4-7: The file currently picks a single User-Agent at module load
and reuses it for all requests; change this by moving the random selection into
the fetchPage function so a new User-Agent is chosen per call. Inside fetchPage,
import or reference the user agents array (e.g., userAgents or USER_AGENTS) and
compute a random index / pick a random element on each invocation, then
set/merge that value into the request headers before performing the fetch;
ensure any existing header-merge logic preserves other headers and that
tests/consumers of fetchPage continue to receive the updated headers per
request.
- Around line 12-18: The test suite needs an explicit assertion that the default
outbound headers and override precedence are passed into fetchSafe: update the
existing custom-header test to spy/mock fetchSafe (the fetchSafe function
exported from the fetchers module) and capture the request init->headers, then
assert the presence and exact values of the default headers (e.g., Accept,
Accept-Language, Upgrade-Insecure-Requests, Sec-Fetch-*) and also assert that
when custom headers are provided they override the defaults; ensure the test
fails if defaults change or override precedence is wrong.
bartholomej
deleted the
bolt-performance-optim-queryselector-6536371311954680762
branch
2 participants
💡 What:
Replaced occurrences of
.querySelectorAll('selector')[0]with.querySelector('selector')insrc/helpers/search.helper.tsandsrc/helpers/creator.helper.ts.🎯 Why:
In
node-html-parser(the DOM parsing library used by this project),querySelectorAllis a significant performance bottleneck when used purely to fetch the first element.querySelectorAllevaluates the CSS selector against the entire DOM subtree and builds an array of all matching nodes before returning.querySelectorstops immediately when the first match is found, avoiding unnecessary traversal and object creation.📊 Impact:
Substantial reduction in execution time and memory allocation during data scraping loops that parse large HTML structures (like Search Results and Creator pages). Stops the parser from wasting CPU cycles evaluating the rest of the document.
🔬 Measurement:
This can be verified via benchmarking the parser speed on large HTML documents or simply by reading
.jules/bolt.mdfor this architectural learning. Tests (yarn test) confirm functionality and Optional Chaining behavior are perfectly preserved.PR created automatically by Jules for task 6536371311954680762 started by @bartholomej
Summary by CodeRabbit