A User Macro for Making Panels Collapsible

[Kmmaughs]

I'm getting a TypeError: Cannot read properties. 

<a id="toggleAll" href="#">Expand/Collapse All sections</a> 
<script type="text/javascript"> 
AJS.$('.panel .collapsible_panel').each(function()
{ 
var panel = AJS.$(this).parent().parent(); 
AJS.$(panel).removeClass('collapsible_panel-open').addClass('collapsible_panel-closed'); 
AJS.$('.collapsible_panel-button', panel).removeClass('expanded'); 
AJS.$('.collapsible_panel-text', panel).text('Expand panel'); 
}); 
</script>