Try encodeURIComponent:
var encodedValue = encodeURIComponent($("#searchbox").val());
$("#resultarea").load("searchresults.php?searchstring=" + encodedValue);
Question
I want to load another page via Javascript like this
$("#resultarea").load("searchresults.php?searchstring=" + $("#searchbox").val());
in searchresults.php, a single statement
echo $_GET["searchstring"];
what I type in searchbox appears when searchresults.php is loaded except when I add space and another word, no thing appear at all. I heared it can be done by encoding or somewhat, I searched but didn't find a solution.
Solution
Try encodeURIComponent:
var encodedValue = encodeURIComponent($("#searchbox").val());
$("#resultarea").load("searchresults.php?searchstring=" + encodedValue);