discord.js - Imagine an app•2w ago

Best practice for object cloning (in TS)?

Looking to get deep copies of things like EmbedBuilder. structuredClone doesn't copy functions. Should we be doing something like const secondEmbed = new EmbedBuilder({...firstEmbed})?

16 Replies

d.js toolkit•2w ago

BotDevOP•2w ago

node ver is 22.12.0 djs ver is 14.24.2 typescript ver is 5.9.3

Mafia•2w ago

is firstEmbed an EmbedBuilder?

BotDevOP•2w ago

Yeah, a previously defined EmbedBuilder with fields, description, contents, or whatever else previously set. I want to be able to make a clone and modify it without side effects polluting the prior embed.

Mafia•2w ago

then just set

const secondEmbed = firstEmbed

const secondEmbed = firstEmbed

BotDevOP•2w ago

Will assignment provide a deep copy by value by default? So if I e.g. tamper with secondEmbed's fields after that, they won't change firstEmbed?

Mafia•2w ago

that is my understanding

BotDevOP•2w ago

Thank you. Will test it out RQ and see. So I tried two things: First:

function editField(embed: EmbedBuilder, field:APIEmbedField): EmbedBuilder {
  const newEmbed = embed;
  let adjustedFields = [... embed.data.fields!]
  
  const fieldIndex = adjustedFields.findIndex(f => f.name === field.name)
  adjustedFields[fieldIndex] = field;
  newEmbed.setFields(adjustedFields);

  return newEmbed;
}

function editField(embed: EmbedBuilder, field:APIEmbedField): EmbedBuilder {
  const newEmbed = embed;
  let adjustedFields = [... embed.data.fields!]
  
  const fieldIndex = adjustedFields.findIndex(f => f.name === field.name)
  adjustedFields[fieldIndex] = field;
  newEmbed.setFields(adjustedFields);

  return newEmbed;
}

This did not work. It tainted the prior EmbedBuilder object. Second, I tried the same thing, but replacing

const newEmbed = embed;

const newEmbed = embed;

with

const newEmbed = new EmbedBuilder(embed.data);

const newEmbed = new EmbedBuilder(embed.data);

, and that worked as expected. However, I am looking for a more general, idiomatic way to accomplish this more uniformly across various objects in the discord.js library.

d.js docs•2w ago

:method: (static) EmbedBuilder#from() discord.js@14.24.2 Creates a new embed builder from JSON data

Mafia•2w ago

this would be another was to go from APIdata to builder

BotDevOP•2w ago

Cool, the #from method looks like it might be used across some other classes like ActionRowBuilder, so that might be the idiom some of the devs want us to use. Just tested

const newEmbed = EmbedBuilder.from(embed);

const newEmbed = EmbedBuilder.from(embed);

and it works the same way as cloning from data. Good stuff. Thank you.

Mafia•2w ago

glad #from worked out went an looked up the source code it is pretty simple

return new this(isJSONEncodable(other) ? other.toJSON() : other);

return new this(isJSONEncodable(other) ? other.toJSON() : other);

BotDevOP•2w ago

In VS Code when I hit f12 on EmbedBuilder to hop to implementation, I see this:

export class EmbedBuilder extends BuildersEmbed {
  public constructor(data?: EmbedData | APIEmbed);
  public override setColor(color: ColorResolvable | null): this;
  public static from(other: JSONEncodable<APIEmbed> | APIEmbed): EmbedBuilder;

export class EmbedBuilder extends BuildersEmbed {
  public constructor(data?: EmbedData | APIEmbed);
  public override setColor(color: ColorResolvable | null): this;
  public static from(other: JSONEncodable<APIEmbed> | APIEmbed): EmbedBuilder;

How'd you wind up landing on that piece of the source? Trying to figure out if there's a convenient way for me to jump there. Short of like going into node_modules and navigating the tree by hand.

BotDevOP•2w ago

Grabbing the code from the code link on https://discord.js.org/docs/packages/discord.js/14.24.2/EmbedBuilder:Class#from ?

discord.js

discord.js is a powerful Node.js module that allows you to interact with the Discord API very easily. It takes a much more object-oriented approach than most other JS Discord libraries, making your bot's code significantly tidier and easier to comprehend.

Mafia•2w ago

ya got it from the docs code link

BotDevOP•2w ago

Good to know. Thank you!

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Best practice for object cloning (in TS)?

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