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index.js
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index.js
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let fetch = require('node-fetch');
let cheerio = require('cheerio');
let url = require('url');
/**
* function isUrl() code sourced from https://github.com/segmentio/is-url
*/
let protocolAndDomainRE = /^(?:\w+:)?\/\/(\S+)$/;
let localhostDomainRE = /^localhost[\:?\d]*(?:[^\:?\d]\S*)?$/
let nonLocalhostDomainRE = /^[^\s\.]+\.\S{2,}$/;
function isUrl(string) {
if (typeof string !== 'string') {
return false;
}
let match = string.match(protocolAndDomainRE);
if (!match) {
return false;
}
let everythingAfterProtocol = match[1];
if (!everythingAfterProtocol) {
return false;
}
if (localhostDomainRE.test(everythingAfterProtocol)) {
return false; // currently my library does not support localhost scanning
}
if (nonLocalhostDomainRE.test(everythingAfterProtocol)) {
return true; // only non localhost urls are valid input for library
}
return false;
}
/*
* For devs
* url - refers to the URL from which <a/> tags are to be extracted
* links - refers to the href values extracted from page pointed by 'url'
*/
function between(x, min, max) {
return x >= min && x <= max;
}
async function linkFilterByStatus(linksArray, status) {
if (!Array.isArray(linksArray)) throw new Error('internal:expected input as array');
let filteredLinks = [];
try {
let results = await Promise.allSettled(linksArray.map(linkObj => {
if (!linkObj.hasOwnProperty('errorFetching'))
return fetch(linkObj.link, { method: 'HEAD' })
else
return new Promise((_, rej) => { rej() })
}));
linksArray.forEach((linkObj, idx) => {
if (results[idx].status === 'fulfilled') {
let returnedStatus = results[idx].value.status;
if (status === 'ALL' || status.includes(returnedStatus))
filteredLinks.push({ ...linkObj, returnedStatus });
}
})
return filteredLinks;
}
catch (err) {
console.log('------------no idea-----------', err);
}
}
async function linkFilterByRange(linksArray, status) {
if (!Array.isArray(linksArray)) throw new Error('internal:expected input as array');
if (!Array.isArray(status)) throw new Error('internal:expected status as array');
let filteredLinks = [];
try {
let results = await Promise.allSettled(linksArray.map(linkObj => {
if (!linkObj.hasOwnProperty('errorFetching'))
return fetch(linkObj.link, { method: 'HEAD' })
else
return new Promise((_, rej) => { rej() })
}));
linksArray.forEach((linkObj, idx) => {
if (results[idx].status === 'fulfilled') {
let returnedStatus = results[idx].value.status;
if (between(returnedStatus, status[0], status[1]))
filteredLinks.push({ ...linkObj, returnedStatus });
}
})
return filteredLinks;
}
catch (err) {
console.log('------------no idea-----------', err);
}
}
function getClass(status) {
if (between(status, 100, 199)) {
return "info";
} else if (between(status, 200, 299)) {
return "success";
} else if (between(status, 300, 399)) {
return "redirect";
} else if (between(status, 400, 499)) {
return "clientErr";
} else if (between(status, 500, 599)) {
return "serverErr"
} else
return "nonStandard";
}
async function linkFilterByClass(linksArray, status) {
if (!Array.isArray(linksArray)) throw new Error('internal:expected input as array');
if (!Array.isArray(status)) throw new Error('internal:expected status as array');
let filteredLinks = [];
try {
let results = await Promise.allSettled(linksArray.map((linkObj) => {
if (!linkObj.hasOwnProperty('errorFetching'))
return fetch(linkObj.link, { method: 'HEAD' })
else
return new Promise((_, rej) => { rej() })
}));
// to fix : this may result in large number of concurrent network requests.
linksArray.forEach((linkObj, idx) => {
if (results[idx].status === 'fulfilled') {
let returnedStatus = results[idx].value.status;
if (status.includes(getClass(returnedStatus)))
filteredLinks.push({ ...linkObj, returnedStatus });
}
})
return filteredLinks;
}
catch (err) {
console.log('------------no idea-----------', err);
}
}
const filter = (linksArray, config) => {
if (Object.keys(config).length === 0) {
config.status = 'ALL'; // flag 'ALL' denotes return all links
return linkFilterByStatus(linksArray, config.status);
}
if (config.hasOwnProperty('status')) {
if (typeof config.status === 'number') {
return linkFilterByStatus(linksArray, [config.status]);
} else if (Array.isArray(config.status)) {
return linkFilterByStatus(linksArray, config.status);
} else {
throw new Error('invalid status value: neither number nor array');
}
} else if (config.hasOwnProperty('statusRange')) {
if (Array.isArray(config.statusRange) && config.statusRange.length == 2
&& (config.statusRange[0] < config.statusRange[1])) {
return linkFilterByRange(linksArray, config.statusRange)
} else {
throw new Error('invalid statusRange value: should be ascending two item array');
}
} else if (config.hasOwnProperty('statusClass')) {
if (typeof config.statusClass === 'string') {
return linkFilterByClass(linksArray, [config.statusClass]);
} else if (Array.isArray(config.statusClass)) {
return linkFilterByClass(linksArray, config.statusClass);
} else {
throw new Error('invalid statusClass value: neither string nor array');
}
} else {
throw new Error('invalid config object property')
}
}
const fetchLinks = async (URL, depth) => {
let links = [];
let httpProtocolMatcher = /^(https?:\/\/)/;
try {
if (!URL.match(httpProtocolMatcher)) throw ({ e: 'url could not be fetched', URL })
const body = await fetch(URL).then(res => res.text()).catch(e => { throw ({ e, URL }) });
let $ = cheerio.load(body);
$('a').each((_, x) => {
links.push($(x).attr('href'))
})
} catch (err) {
links.push("~" + err.URL) // to identify this URL fetching failed
}
links = links.reduce((acc, link) => {
if (link === undefined) return acc; // this too returned sometimes.
if (link[0] === "~") {
acc.push({ link: URL, errorFetching: true });
}
else
acc.push({ link: url.resolve(URL, link), linkFoundOn: URL });
return acc;
}, []);
if (depth == 0) return links;
let recLinkResults = links;
let tmp = [];
for (let i = 0; i < links.length; i++) {
if (!links[i].hasOwnProperty("errorFetching")) {
tmp = await fetchLinks(links[i].link, depth - 1);
} else {
tmp = [];
}
recLinkResults = recLinkResults.concat(tmp);
}
return recLinkResults;
}
const livink = async (string, config = {}) => {
if (typeof string !== 'string') throw new Error('URL must be in string format');
if (!isUrl(string)) throw new Error('invalid URL');
const URL = string; // validation of string as url completed
if (typeof config !== 'object') {
throw new Error('config must be an object');
}
if (Object.keys(config).length === 0) {
config.depth = 0;
}
if (Object.keys(config).length > 1 && !config.hasOwnProperty('depth')) {
throw new Error('invalid config object passed');
}
if (typeof config.depth !== 'number' || (config.depth < 0 || config.depth > 2)) {
throw new Error('Depth should be a number between 0 and 2(included)');
}
return fetchLinks(URL, config.depth);
}
module.exports = {
livink,
filter
}