denoland-deno/docs/examples/manage_dependencies.md

Managing Dependencies

In Deno there is no concept of a package manager as external modules are imported directly into local modules. This raises the question of how to manage remote dependencies without a package manager. In big projects with many dependencies it will become cumbersome and time consuming to update modules if they are all imported individually into individual modules.

The standard practice for solving this problem in Deno is to create a deps.ts file. All required remote dependencies are referenced in this file and the required methods and classes are re-exported. The dependent local modules then reference the deps.ts rather than the remote dependencies.

This enables easy updates to modules across a large codebase and solves the 'package manager problem', if it ever existed. Dev dependencies can also be managed in a separate dev_deps.ts file.

deps.ts example

/**
 * deps.ts re-exports the required methods from the remote Ramda module.
 **/
export {
  add,
  multiply,
} from "https://x.nest.land/ramda@0.27.0/source/index.js";

In this example the same functionality is created as is the case in the local and remote import examples. But in this case instead of the Ramda module being referenced directly it is referenced by proxy using a local deps.ts module.

Command: deno run dependencies.ts

import {
  add,
  multiply,
} from "./deps.ts";

function totalCost(outbound: number, inbound: number, tax: number): number {
  return multiply(add(outbound, inbound), tax);
}

console.log(totalCost(19, 31, 1.2));
console.log(totalCost(45, 27, 1.15));

/**
 * Output
 *
 * 60
 * 82.8
 */