CODEWITHSUNDEEP
node.jsdiscord.js
Jay
Jay

Reputation: 51

SyntaxError: Unexpected Token '?' discord.js

I'm using discord.js version 12.5.3, I also am using replit for my project. I keep getting this error: enter image description here

This is my code:

export default class Deps {
  static #instances = new Map();

  static get(type) {
    return this.#instances.get(type)
      ?? this.add(type, new type());
  }

  static add(type, instance) {
    return this.#instances
      .set(type, instance)
      .get(type);
  }
}

Upvotes: 0

Views: 299

Answers (1)

Dai
Dai

Reputation: 154995

Short answer: The ?? needs to be on the same line as the return statement:

export default class Deps {
  static #instances = new Map();

  static get(type) {
    return this.#instances.get(type) ?? this.add(type, new Type()); // <-- Like this
  }

  static add(type, instance) {
    return this.#instances
      .set(type, instance)
      .get(type);
  }
}

Longer answer: The return statement in JavaScript has special automatic semicolon insertion ("ASI") rules which mean you need to have the entire expression on a single line, or use parentheses so that your return statement's expression clearly spans multiple lines.

So you could also do this:

export default class Deps {
  static #instances = new Map();

  static get(type) {
    return ( this.#instances.get(type)    // <-- Opening `(` here.
        ?? this.add(type, new Type())
    );                                    // <-- Closing `)` here.
  }

  static add(type, instance) {
    return this.#instances
      .set(type, instance)
      .get(type);
  }
}

Before I started using TypeScript I used to get stung by return ASI rules all the time without realising it: it's a frequent source of bugs.

Upvotes: 1

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