Use

You might want to separate certain pieces of code that can be used by different APIs, such as sending emails or connecting to a database. In Milkio, the best way to achieve this is by writing them as “uses”. Typically, we place these “uses” under the /src/uses directory, but you can actually place them anywhere, including within the /src/apps directory.

Lifecycle

Each “use” is a singleton and lazily loaded. It is only executed the first time it is used and only executed once. Subsequent calls will return the same content as the initial call.

Writing

As a convention, we prefix the variable names exported by each feature with “use”. Let’s take an addition and subtraction calculator as an example:

import { defineUse } from "milkio";

export const useCalculator = defineUse(async () => {
  return {
    add(a, b) {
      return a + b;
    },
    subtract(a, b) {
      return a - b;
    },
    // ...
  };
});

You can call it from anywhere in your code:

const calculator = await useCalculator();

calculator.add(1, 3); // Output: 4
calculator.subtract(1, 3); // Output: -2