added documentation for passing arguments to event handlers

Author: sw-yx

content/docs/handling-events.md

@@ -139,3 +139,17 @@ 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
+
+Inside a loop it is common to want to pass a param to an event handler. For example if `i` is the row id:
+
+```js
+<button onClick={() => this.deleteRow(i)}>Delete Row</button> 
+```
+
+or alternatively (especially if you want to avoid triggering a re-render in a child component):
+
+```js
+<button onClick={this.deleteRow.bind(this,i)}>Delete Row</button>
+```