📝 Fix code style issue

* Change `var` to `let`.
* Change `function() {}` to `() => {}`.
* Use shorthand function syntax on object notation.
* Remove spaces between object notation brackets.
* Small fixes.

docs/api/process.md

@@ -32,7 +32,7 @@ the global scope when node integration is turned off:
 // preload.js
 const _setImmediate = setImmediate;
 const _clearImmediate = clearImmediate;
-process.once('loaded', function() {
+process.once('loaded', () => {
   global.setImmediate = _setImmediate;
   global.clearImmediate = _clearImmediate;
 });