resolve-url.macro

Resolve your URLs during build

This macro allows you to resolve the URLs from the back end (e.g. a Django app) in the client-side JS code. Thanks to that the URLs can be verified at the build time, and only used URLs will appear in the code.

Getting started

First of all, you'll need Babel.

Then, install babel-plugin-macros together with this package:

yarn add -D resolve-url.macro babel-plugin-macros
# or
npm install -D resolve-url.macro babel-plugin-macros

Finally, add a configuration file in the root of your project, called babel-plugin-macros.config.js:

module.exports = {
  resolve: {
    urlsPath: 'path/to/urls',
  },
};

This is it for the configuration, but what's inside the URLs file?

The URLs file

This file should contain a list of available URLs. Each URL should consist of:

a name: e.g. "login", "get-me-that-data",
a template: e.g. "/login", "/items/${id}"

As for the format, it can be either a JS file:

module.exports = [
  {
    name: 'no-params',
    template: 'params/zero/',
  },
  {
    name: 'three-params',
    template: 'params/three/${first}-${second}/${third}/',
  },
];

or a JSON file:

[
  {
    "name": "no-params",
    "template": "params/zero/"
  },
  {
    "name": "three-params",
    "template": "params/three/${first}-${second}/${third}/"
  }
]

The parts of the URL wrapped in ${} will be recognized as URL parameters.

Such a file will most probably be produced by another tool (coming soon!).

Using in the code

As with other macros built on babel-plugin-macros, you'll need to import the macro. After that just use it as a function:

import resolveUrl from 'resolve-url.macro';

axios.post(resolveUrl('three-params', 2 + 2, -1, 'quick maths'), data);

Under the hood the URL will be inlined using the configuration and will turn into something like this:

axios.post(`params/three/${2 + 2}-${-1}-${'quick maths'}`, data);

The number of parameters has to match the predefined URL template. Notice that the expressions are preserved and will be computed at runtime.

Passing query parameters

A common pattern while working with URLs is the need to pass query parameters. You can do that easily with the mecro too, using the withQuery property:

import resolveUrl from 'resolve-url.macro';

axios.post(resolveUrl.withQuery('search', { sortBy: 'id' }), data);

The last argument will be used to build the query string.

All properties of the query object will be properly escaped:

// query object
{ redirect_url: 'https://example.com/foobar' }

// result
'?redirect_url=https%3A%2F%2Fexample.com%2Ffoobar'

Null and undefined values will be ignored:

// query object
{ foo: null, bar: 42 }

// result
'?bar=42'

Using the object parameter

It's also possible to pass an object as a parameter to the resolveUrl function. In that case property names have to match parameters from the URL template:

import resolveUrl from 'resolve-url.macro';

axios.get(resolveUrl('get-object', { userId, objectId }));

In such a situation the object has to be the last argument.

Info for contributors

Everyone is welcome to contribute to the package - just be nice.

After cloning the repo you'll have a few commands useful in development:

lint - just lints (using ESLint and Prettier)
lint:fix - lints and fixes what's possible; use it especially for autoformatting
test - tests the code using Jest
test:update - test and updates the snapshots if they've changed