I have a script that reads in some JSON data:

```
var tempJson;
$.post("scripts/getJSON.php", function(data) {
     tempJson = data;
}, 'json');
alert("");  //First alert
alert("That: " + tempJson);  //Second alert

```

When I include the first alert line, the second alert gives me an [Object object] as expected. When I omit the first alert line, I receive undefined in the second alert. Why?