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scraper.js
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scraper.js
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"use strict";
class HtmlHelper {
constructor(){
this._domparser = new DOMParser();
}
parse = (text) => {
return this._domparser.parseFromString(text, "text/html");
};
/**
* Fetch and pre-parse an HTML document at the given URL
*/
getDocument = async (documentUrl) => {
const res = await fetch(documentUrl);
const text = await res.text();
return this.parse(text);
};
/**
* Remove HTML noise like `\n` from the given string
*/
cleanText = (str) => (
str
.replaceAll(" ", "")
.replaceAll("\n", "")
.replaceAll(" ", "")
.trim()
);
};
class Scraper {
constructor(){
this._htmlHelper = new HtmlHelper();
this._activeUrl = this._getActiveUrl();
this._baseUrl = this._getBaseUrl();
};
_getBaseUrl = () => {
return document.location.origin;
};
_getActiveUrl = () => {
return document.location.href;
};
_getActiveDocument = async () => {
return this._htmlHelper.getDocument(this._activeUrl);
};
// -- Sections --
_getAllSectionElements = (doc) => {
return Array.from(doc.getElementsByClassName("course-section"));
};
_generateSectionTitle = (sectionElement, sectionIndex) => {
return this._htmlHelper.cleanText(
`${sectionIndex} ${sectionElement.querySelector('[class="section-title"]').innerText}`
);
};
_getSectionPageElements = (sectionElement) => {
return Array.from(sectionElement.getElementsByClassName("section-list")[0].children);
};
// -- Pages --
_getPageTitle = (pageElement) => {
return this._htmlHelper.cleanText(pageElement.querySelector(".item .title-container").innerText);
};
_getPageUrl = (pageElement) => {
return this._baseUrl + pageElement.getAttribute("data-lecture-url");
};
_getPageInfo = (pageElement) => {
const pageTitle = this._getPageTitle(pageElement);
const pageUrl = this._getPageUrl(pageElement);
return {
pageTitle,
pageUrl
};
};
_getPageDownloadInfo = async (pageInfo) => {
const doc = await this._htmlHelper.getDocument(pageInfo.pageUrl);
const downloadButton = doc.getElementsByClassName("download")[0];
if(!downloadButton) return {
downloadUrl: ""
};
const downloadUrl = downloadButton.href;
const downloadFileName = downloadButton.getAttribute("data-x-origin-download-name");
return {
downloadUrl,
downloadFileName
};
};
// Orchestration
_getSectionPageInfos = (sectionElement) => {
const sectionPageElements = this._getSectionPageElements(sectionElement);
return sectionPageElements.map(this._getPageInfo);
};
_getCourseSectionPageInfos = (sectionElements) => {
return sectionElements.map((s, idx) => {
const sectionTitle = this._generateSectionTitle(s, idx);
const sectionPageInfos = this._getSectionPageInfos(s);
return {
sectionTitle,
sectionPageInfos
};
});
};
_getSectionPagesDownloadInfos = async (sectionPageInfos) => {
const downloadInfos = await Promise.all(sectionPageInfos.map(this._getPageDownloadInfo));
const filteredInfos = downloadInfos.filter((info) => info.downloadUrl != "");
return filteredInfos;
};
_getCoursePageDownloadInfos = async (courseInfo) => {
return Promise.all(courseInfo.map(async ({ sectionTitle, sectionPageInfos }) => {
const pageDownloadInfos = await this._getSectionPagesDownloadInfos(sectionPageInfos);
return {
sectionTitle,
content: pageDownloadInfos
};
}));
};
scrapeCourseDownloads = async () => {
const activeDoc = await this._getActiveDocument();
const sections = this._getAllSectionElements(activeDoc);
const courseInfo = this._getCourseSectionPageInfos(sections);
const courseDownloads = await this._getCoursePageDownloadInfos(courseInfo);
console.log(JSON.stringify(courseDownloads));
};
}
new Scraper().scrapeCourseDownloads();