Applies to all PHPRunner, ASPRunner.NET and ASPRunnerPro.
You can change the label of the custom button from any Javascript event i.e. from Javascript OnLoad. As a first step you need to find Item ID of this button. The following screenshot explains how to do this and in our example Item ID is custom_button.
Now here is the code that changes the label:
$("span[data-itemid=custom_button]").find("a").text("New Label");