Improve ESM import support (knex#4350)

Author: kibertoad

README.md

@@ -116,3 +116,33 @@ try {
   // error handling
 }
 ```
+
+## Usage as ESM module
+
+If you are launching your Node application with `--experimental-modules`, `knex.mjs` should be picked up automatically and named ESM import should work out-of-the-box.
+Otherwise, if you want to use named imports, you'll have to import knex like this:
+```js
+import { knex } from 'knex/knex.mjs'
+```
+
+You can also just do the default import:
+```js
+import knex from 'knex'
+```
+
+If you are not using TypeScript and would like the IntelliSense of your IDE to work correctly, it is recommended to set the type explicitly:
+```js
+/**
+ * @type {Knex}
+ */
+const database = knex({
+    client: 'mysql',
+    connection: {
+      host : '127.0.0.1',
+      user : 'your_database_user',
+      password : 'your_database_password',
+      database : 'myapp_test'
+    }
+  });
+database.migrate.latest();
+```

knex.mjs

@@ -0,0 +1,11 @@
+// Knex.js
+// --------------
+//     (c) 2013-present Tim Griesser
+//     Knex may be freely distributed under the MIT license.
+//     For details and documentation:
+//     http://knexjs.org
+
+import knex from './lib/index.js';
+
+export { knex }
+export default knex

package.json

@@ -2,7 +2,7 @@
   "name": "knex",
   "version": "0.95.1",
   "description": "A batteries-included SQL query & schema builder for Postgres, MySQL and SQLite3 and the Browser",
-  "main": "knex.js",
+  "main": "knex",
   "types": "types/index.d.ts",
   "engines": {
     "node": ">=10"