Error occurred while parsing your function triggers - firebase

Question

The following error is shown while deploying firebase function.
I tried initializing the firebase functions.
I also double-checked the index.js file.
I'm new to deploying firebase functions so please help me for the same.
index.js is as follows:
const functions = require('firebase-functions');
// replaces keywords with emoji in the "text" key of messages
// pushed to /messages
exports.emojify =
functions.database.ref('/messages/{pushId}/text')
.onWrite(event => {
// Database write events include new, modified, or deleted
// database nodes. All three types of events at the specific
// database path trigger this cloud function.
// For this function we only want to emojify new database nodes,
// so we'll first check to exit out of the function early if
// this isn't a new message.
// !event.data.val() is a deleted event
// event.data.previous.val() is a modified event
if (!event.data.val() || event.data.previous.val()) {
console.log("not a new write event");
return;
}
// Now we begin the emoji transformation
console.log("emojifying!");
// Get the value from the 'text' key of the message
const originalText = event.data.val();
const emojifiedText = emojifyText(originalText);
// Return a JavaScript Promise to update the database node
return event.data.ref.set(emojifiedText);
});
// Returns text with keywords replaced by emoji
// Replacing with the regular expression /.../ig does a case-insensitive
// search (i flag) for all occurrences (g flag) in the string
function emojifyText(text) {
var emojifiedText = text;
emojifiedText = emojifiedText.replace(/\blol\b/ig, "😂");
emojifiedText = emojifiedText.replace(/\bcat\b/ig, "😸");
return emojifiedText;
}

Answer 1

Please check the current documentation on triggers, and specifically on migration from Beta to Version 1.0 .
event.data.previous.val() has changed to change.before.val()
event.data.val() has changed to change.after.val()
Also, the Promise statement changes to:
return change.after.ref.parent.child('text').set(emojifiedText);
The complete index.js looks like:
const functions = require('firebase-functions');
// replaces keywords with emoji in the "text" key of messages
// pushed to /messages
exports.emojify=
functions.database.ref('/messages/{pushId}/text')
.onWrite((change,context)=>{
// Database write events include new, modified, or deleted
// database nodes. All three types of events at the specific
// database path trigger this cloud function.
// For this function we only want to emojify new database nodes,
// so we'll first check to exit out of the function early if
// this isn't a new message.
// Only edit data when it is first created.
if (change.before.exists()){
return null;
}
// Exit when the data is deleted.
if (!change.after.exists()){
return null;
}
// Now we begin the emoji transformation
console.log("emojifying!");
//Get the value from the 'text' key of the message
const originalText = change.after.val();
const emojifiedText = emojifyText(originalText);
//Return a JavaScript Promise to update the database nodeName
return change.after.ref.parent.child('text').set(emojifiedText);
});
// Returns text with keywords replaced by emoji
// Replacing with the regular expression /.../ig does a case-insensitive
// search (i flag) for all occurrences (g flag) in the string
function emojifyText(text){
var emojifiedText=text;
emojifiedText=emojifiedText.replace(/\blol\b/ig,"😂");
emojifiedText=emojifiedText.replace(/\bcat\b/ig,"😸");
return emojifiedText;
}