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ravisiyer/app.js

Created March 30, 2024 09:48
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Barebones blogger blog feed to set of posts (book) using JavaScript and bypassing CORS by using a Node Express proxy server
Raw
app.js
const express = require("express");
const cors = require("cors");
const { createProxyMiddleware } = require("http-proxy-middleware");
const app = express();
app.use(cors());
app.use(
"/",
createProxyMiddleware({
target: "https://sathyasaiwithstudents.blogspot.com",
changeOrigin: true,
logger: console,
logLevel: "debug",
})
);
app.listen(3001, () => {
console.info("proxy server is running on port 3001");
});
Raw
index.html
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8" />
<meta name="viewport" content="width=device-width, initial-scale=1.0" />
<title>Document</title>
</head>
<body>
<main id="main"></main>
<script src="script.js"></script>
</body>
</html>
Raw
script.js
// Modified version of https://github.com/hn-88/bloggerToEbook
// Dealing with CORS Errors in JavaScript,
// https://codedamn.com/news/javascript/javascript-cors-error-handling
// suggests proxy server written using Node express as a way to get around CORS
var proxyURL = "http://localhost:3001/"; //Using Node Express local proxy
// Proxy maps requests to https://sathyasaiwithstudents.blogspot.com
// So blog URL need not be passed in fetch request in this program
var forbiddenErrorMsg = `<p>Got 'Forbidden (403)' response.</p>`;
var searchLabel = "3.%20Conversations";
var contentHTML = "";
var mainElement = document.getElementById("main");
async function myFunction() {
var feedReqURL =
proxyURL +
"feeds/posts/default/-/" +
searchLabel +
"?max-results=2&alt=json";
// "feeds/posts/default/" +
// "?max-results=100&alt=json";
var options = {
method: "GET",
muteHttpExceptions: true,
};
var data;
var temp = feedReqURL;
console.log(temp);
try {
response = await fetch(temp, options);
console.log("response");
console.log(response);
if (!response.ok) {
if (response.status === 403) {
mainElement.innerHTML = forbiddenErrorMsg;
} else {
console.log(
"response.ok is false with response.status != 403! Aborting function!"
);
}
return;
}
let data = await response.json();
console.log("data");
console.log(data);
var contentHTML = "";
for (i in data.feed.entry) {
contentHTML +=
"<h1>" +
data.feed.entry[i].title.$t +
"</h1>" +
data.feed.entry[i].content.$t +
'<span style="page-break-after: always" />';
}
// console.log("contentHTML");
// console.log(contentHTML);
mainElement.innerHTML = contentHTML;
} catch (error) {
mainElement.innerHTML = error;
console.log("error");
console.log(error);
}
}
if (mainElement) {
console.log("Calling myFunction");
myFunction();
} else {
alert("main element not found! Aborting!");
}
@ravisiyer
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Author

This is a HTML/JavaScript modified (and simplified) version of Google Apps Script based https://github.com/hn-88/bloggerToEbook . Key feature of this program is bypassing CORS restriction/error using a Node Express proxy server created using http-proxy-middleware node package. For more on latter, see section "2. Using a proxy server" in https://codedamn.com/news/javascript/javascript-cors-error-handling . To use the program, first the node proxy server has to be run ('node app.js'). Then the index.html file has to be opened in a browser.
Related blog post: Notes on bypassing CORS restriction (error) in JavaScript code that fetches blogger blog feed

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