javascript - How to call function in an HTML attribute that only accepts string values / literals? -

i having issues calling function within attribute in jade file:

test.jade

script     - function myfunction(str) {         regex on str, say, filter out full stops ,          return new string.     }      .container-fluid         .row             .col-md-12                 div(ng-repeat='thing in things')                     button(popovertext='{{thing.description()}}', popover-trigger='mouseenter') 

the expression in popovertext attribute prints strings fine each thing in things (as done ng-repeat) without calling function. far i'm told, popovertext accepts string values, when did like

                    button(popovertext='myfunction({{thing.description()}})') 

it prints out myfunction(....the original string....), means doesn't recognise function @ all. i'm supposed call function in jade file , not externally in .js file, because apparently attribute doesn't have 'ng-' doesn't communicate controllers @ all?

how can possibly around this?

---

also, confused regarding when should put "-" in front of line of code. right in saying that, jade, need var, function, , return?

a possible way around setting field called descriptionstring thing object. can in controller:

angular.foreach(things, function(thing){   thing.descriptionstring = thing.description(); }); 

the rest easy:

button(popovertext='{{thing.descriptionstring}}', popover-trigger='mouseenter')