8a6e9070e0
* docs: add jsdoc * feat: change enums to as const objects * chore(test): add themeColors.test.ts * fix: fix tests and bugs with strings.ts util * fix: path alias imports and tsconfig file bug * fix: remove --max-warnings 0
87 lines
3.3 KiB
TypeScript
87 lines
3.3 KiB
TypeScript
import getCourseTableRows from './getCourseTableRows';
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const NEXT_PAGE_BUTTON_SELECTOR = '#next_nav_link';
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const PREV_PAGE_BUTTON_SELECTOR = '#prev_nav_link';
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/**
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* Represents all the states that we care about when autoloading the next page of courses
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*/
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export const AutoLoadStatus = {
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LOADING: 'LOADING',
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IDLE: 'IDLE',
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ERROR: 'ERROR',
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DONE: 'DONE',
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} as const;
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/**
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* Represents the type of the auto load status.
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* It is a union type that includes all the values of the AutoLoadStatus object.
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*/
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export type AutoLoadStatusType = (typeof AutoLoadStatus)[keyof typeof AutoLoadStatus];
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let isLoading = false;
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let nextPageURL = getNextButton(document)?.href;
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/**
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* This will scrape the pagination buttons from the course list and use them to load the next page
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* and then return the table rows from the next page
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* @returns a tuple of the current LoadStatus (whether are currently loading the next page, or if we have reached the end of the course catalog,
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* or if there was an error loading the next page) and an array of the table rows from the next page (or an empty array
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* if we have reached the end of the course catalog
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*/
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export async function loadNextCourseCatalogPage(): Promise<[AutoLoadStatusType, HTMLTableRowElement[]]> {
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// if there is no more nextPageURL, then we have reached the end of the course catalog, so we can stop
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if (!nextPageURL) {
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return [AutoLoadStatus.DONE, []];
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}
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// remove the next button so that we don't load the same page twice
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removePaginationButtons(document);
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if (isLoading) {
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// if we are already loading the next page, then we don't need to do anything
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return [AutoLoadStatus.LOADING, []];
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}
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// begin loading the next page
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isLoading = true;
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try {
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const response = await fetch(nextPageURL);
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const html = await response.text();
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const parser = new DOMParser();
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const newDocument = parser.parseFromString(html, 'text/html');
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// extract the table rows from the document of the next page
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const tableRows = getCourseTableRows(newDocument);
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if (!tableRows) {
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return [AutoLoadStatus.ERROR, []];
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}
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// extract the next page url from the document of the next page, so when we scroll again we can use that
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nextPageURL = getNextButton(newDocument)?.href;
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isLoading = false;
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return [AutoLoadStatus.IDLE, Array.from(tableRows)];
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} catch (e) {
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console.error(e);
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return [AutoLoadStatus.ERROR, []];
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}
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}
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/**
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* Scrapes the next button from the document
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* @param doc the document to get the next button from
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* @returns the next button from the document
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*/
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function getNextButton(doc: Document) {
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return doc.querySelector<HTMLAnchorElement>(NEXT_PAGE_BUTTON_SELECTOR);
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}
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/**
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* Removes the next and previous buttons from the document so that we don't load the same page twice
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* @param doc the document to remove the next and previous buttons from
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*/
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export function removePaginationButtons(doc: Document) {
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const nextButton = doc.querySelectorAll<HTMLAnchorElement>(NEXT_PAGE_BUTTON_SELECTOR);
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nextButton.forEach(button => button.remove());
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const prevButton = doc.querySelectorAll<HTMLAnchorElement>(PREV_PAGE_BUTTON_SELECTOR);
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prevButton.forEach(button => button.remove());
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}
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