Implementation Steps

Name, Service, Conditions, Event Handler
Name:makeUppercase, Realtime Database, Trigger on specific path, makeUppercase handler

const functions = require('firebase-functions');

exports.emojify = functions.database.ref('/messages/{pushId}/text')
	.onWrite(event => {
		if(!event.data.val()|| event.data.previous.val()){
			console.log("not a new write event");
			return;
		}

		console.log("emojifying");

		const originalText = event.data.val();
		const emojifiedText = emojifyText(originalText);

		return event.data.ref.set(emojifiedText);
	});

	function emojifyText(text){
		var emojifiedText = text;
		emojifiedText = emojifiedText.replace(/\blob\b/id, "");
		emojifiedText = emojifiedText.replace(/\blob\b/id, "");
		return emojifiedText;
	}