CODEWITHSUNDEEP
javascriptnode.jsfunctionparametersoverloading
GenerationTech
GenerationTech

Reputation: 89

Javascript in Node.js using functions with different signatures

What's the difference between query(userOptions) and query(...args) ? I get that they are probably overloads for the same function call, but I'm not sure how they would be actually called or under what circumstances in a calling program to select which overload is used, especially with the static decoration.

class Gamedig {
    constructor() {
        this.queryRunner = new QueryRunner();
    }

    async query(userOptions) {
        return await this.queryRunner.run(userOptions);
    }

    static getInstance() {
        if (!singleton) singleton = new Gamedig();
        return singleton;
    }
    static async query(...args) {
        return await Gamedig.getInstance().query(...args);
    }
}

Upvotes: 1

Views: 687

Answers (1)

Felix Kling
Felix Kling

Reputation: 816364

static means that the function is assigned to the constructor, i.e. Gamedig. The function is called as 

Gamedig.query(...)

Without static the function is accessible on an instance if Gamedig, i.e.

var instance = new Gamedig();
instance.query(...);

JavaScript doesn't support function overloading.

userOptions vs ...args has nothing to do with that. The rest parameter in a function definition means that the function accepts a variable number of arguments and they are all collected in an array which is assigned to that parameter (args in your example).

Example:

function foo(...bar) {
  console.log(bar);
}

foo(1);
foo(1,2);
foo(1,2,3);

Upvotes: 2

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