Tweak the event doc

Author: gaearon

content/docs/handling-events.md

@@ -140,11 +140,15 @@ class LoggingButton extends React.Component {
 
 The problem with this syntax is that a different callback is created each time the `LoggingButton` renders. In most cases, this is fine. However, if this callback is passed as a prop to lower components, those components might do an extra re-rendering. We generally recommend binding in the constructor or using the class fields syntax, to avoid this sort of performance problem.
 
-## Passing arguments to event handlers
+## Passing Arguments to Event Handlers
 
-Inside a loop it is common to want to pass a param to an event handler. For example, if `i` is the row id, either of the following would work:
+Inside a loop it is common to want to pass an extra parameter to an event handler. For example, if `id` is the row ID, either of the following would work:
 
 ```js
-<button onClick={() => this.deleteRow(i)}>Delete Row</button>
-<button onClick={this.deleteRow.bind(this, i)}>Delete Row</button>
+<button onClick={(e) => this.deleteRow(id, e)}>Delete Row</button>
+<button onClick={this.deleteRow.bind(this, id)}>Delete Row</button>
 ```
+
+The above two lines are equivalent, and use [arrow functions](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Functions/Arrow_functions) and [`Function.prototype.bind`](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_objects/Function/bind) respectively.
+
+In both cases, the `e` argument representing the React event will be passed as a second argument after the ID. With an arrow function, we have to pass it explicitly, but with `bind` any further arguments are automatically forwarded.