Create a RSS feed using Firebase

Here is the skeleton of a RSS file format:

rss
<rss version="2.0">
    <channel>
        <title>Erik Martín Jordán</title>
        <link>https://erikmartinjordan.com</link>
        <description>Code, web development, tech and off-topic</description>
        <item>
            <title><![CDATA[ Quick way to transform a number into a string using JavaScript ]]></title>
            <link>https://erikmartinjordan.com/quick-way-number-string-javascript</link>
            <description><![CDATA[ Quick way to transform a number into a string using JavaScript. ]]></description>
        </item>
        <item>
            <title><![CDATA[ onBlur prevents onClick to execute ]]></title>
            <link>https://erikmartinjordan.com/onblur-prevents-onclick-react</link>
            <description><![CDATA[ Two solutions on how to prevent the onBlur event cancelling the onClick. ]]></description>
        </item>
    </channel>
</rss>

In this example, I will configure the file to display the RSS from https://erikmartinjordan.com/rss.xml.

Server configuration

The first step is to configure the Firebase server editing firebase.json:

json
"rewrites": [
    {
        "source": "/rss.xml",
        "function": "buildRSS"
    },
    {
        "source": "/sitemap.xml",
        "function": "buildSitemap"
    },
    {
        "source": "!/sitemap.xml && !/rss.xml",
        "function": "preRender"
    }
]

If the user accesses /rss.xml, Firebase will run the buildRSS function. Whereas if the user accesses /sitemap.xml, Firebase will run the buildSitemap function.

Otherwise, it'll display a normal page using the preRender function. If you don't know what a preRender function does, you can check this post.

Creating the function

We'll create a Firebase function in ../functions/index.js.

This function returns a string with the sitemap info:

javascript
exports.buildRSS = functions.https.onRequest((request, response) => {

    let rssHeader = `<?xml version="1.0" encoding="UTF-8"?><rss version="2.0"><channel>`

    let title = `<title>Erik Martín Jordán</title>`

    let link = `<link>https://erikmartinjordan.com</link>`

    let description = `<description>Code, web development, tech and off-topic</description>`

    // You can also generate the posts dinamically using a loop and Firebase's database
    let posts = `<item><title><![CDATA[ Quick way to transform a number into a string using JavaScript ]]></title><link>https://erikmartinjordan.com/quick-way-number-string-javascript</link><description><![CDATA[ Quick way to transform a number into a string using JavaScript. ]]></description></item><item><title><![CDATA[ onBlur prevents onClick to execute ]]></title><link>https://erikmartinjordan.com/onblur-prevents-onclick-react</link><description><![CDATA[ Two solutions on how to prevent the onBlur event cancelling the onClick. ]]></description></item>`

    let rssFooter = `</channel></rss>`

    let rssString = rssHeader + title + link + description + posts + rssFooter

    response.set('Content-Type', 'text/xml')
    response.status(200).send(rssString)

})