Javascript – Fetch message from the client Discord.js

discorddiscord.jsjavascriptnode.js

I have searched for this question and the hundreds of responses that I've found only speak of this in the terms of within the message event
E.G.

client.on('message', message => {
   message.id // <<< I don't think this is the right code for it but that's not the point I'm making so....
});

However, I need to access a message via its id without using the message event. Specifically, I need to within the messageReactionAdd event however I would much rather learn how to get it from the client because I've needed to do the same thing in the past as well (but instead I was forced to redesign my original plans).
This is the code that I've tried using but it just won't work:

client.channels.cache.get("Channel_Id").messages.fetch("Message_Id");

I was led to this code string from a different project where I found the first message in a channel:

client.channels.cache.get("Channel_Id").messages.fetch({ limit: 1 }).then(messages => {var lastMessage = messages.first();});

Is this even possible? I find it a little strange that there isn't an easy way to just target a message directly without jumping through a bunch of hoops (like client.messages.fetch("Message_Id")). Any help would be much appreciated.

Best Answer

The first version of fetching should work. Note however, that messageReactionAdd event is emitted only for messages that are cached by your bot. Cached messages are those that are received after you start up your bot, up to (by default) 200 messages per channel.

If you want to fetch only one specific message to receive reaction events for, this should work, as long as it's in a channel that you don't have to worry about mentioned earlier limit.

However, as you are using v12, there is a feature that allows to receive events for uncached structure called Partials (here is the guide page for it). If you enable partials, you can receive events for your message without the need to fetch it beforehand. Just remember that you receive only IDs this way, but with ability to fetch if needed.

Native deep cloning

It's called "structured cloning", works experimentally in Node 11 and later, and hopefully will land in browsers. See this answer for more details.

Fast cloning with data loss - JSON.parse/stringify

If you do not use Dates, functions, undefined, Infinity, RegExps, Maps, Sets, Blobs, FileLists, ImageDatas, sparse Arrays, Typed Arrays or other complex types within your object, a very simple one liner to deep clone an object is:

JSON.parse(JSON.stringify(object))

const a = {
  string: 'string',
  number: 123,
  bool: false,
  nul: null,
  date: new Date(),  // stringified
  undef: undefined,  // lost
  inf: Infinity,  // forced to 'null'
  re: /.*/,  // lost
}
console.log(a);
console.log(typeof a.date);  // Date object
const clone = JSON.parse(JSON.stringify(a));
console.log(clone);
console.log(typeof clone.date);  // result of .toISOString()

See Corban's answer for benchmarks.

Reliable cloning using a library

Since cloning objects is not trivial (complex types, circular references, function etc.), most major libraries provide function to clone objects. Don't reinvent the wheel - if you're already using a library, check if it has an object cloning function. For example,

lodash - cloneDeep; can be imported separately via the lodash.clonedeep module and is probably your best choice if you're not already using a library that provides a deep cloning function
AngularJS - angular.copy
jQuery - jQuery.extend(true, { }, oldObject); .clone() only clones DOM elements
just library - just-clone; Part of a library of zero-dependency npm modules that do just do one thing. Guilt-free utilities for every occasion.

ES6 (shallow copy)

For completeness, note that ES6 offers two shallow copy mechanisms: Object.assign() and the spread syntax. which copies values of all enumerable own properties from one object to another. For example:

var A1 = {a: "2"};
var A2 = Object.assign({}, A1);
var A3 = {...A1};  // Spread Syntax

Javascript – Remove properties from objects (JavaScript)

To remove a property from an object (mutating the object), you can do it like this:

delete myObject.regex;
// or,
delete myObject['regex'];
// or,
var prop = "regex";
delete myObject[prop];

Demo

var myObject = {
    "ircEvent": "PRIVMSG",
    "method": "newURI",
    "regex": "^http://.*"
};
delete myObject.regex;

console.log(myObject);

For anyone interested in reading more about it, Stack Overflow user kangax has written an incredibly in-depth blog post about the delete statement on their blog, Understanding delete. It is highly recommended.

If you'd like a new object with all the keys of the original except some, you could use the destructuring.