arguments.callee in scala.js -

i porting javascript function scala.js:

once: function (el, type, callback) {   var typearray = type.split(' ');   (var = typearray.length - 1; >= 0; i--) {     el.addeventlistener(typearray[i], function(e) {       e.target.removeeventlistener(e.type, arguments.callee);       return callback(e);     });   }; }, 

here attempt @ writing scala code:

def once(element: topnode, tpe: string, callback: function1[event,any]): unit = {   tpe.split(" ").foreach(item => element.addeventlistener(item, (e : event) => {     e.target.removeeventlistener(e.`type`, ?) // <-- put here?     callback(e)   })) } 

how can reference lambda in place holder?

scala.js not have equivalent of arguments.callee of javascript. more generally, not have equivalent of arguments. lambda cannot read reference itself, unless given via captured environment. can achieved storing lambda in val in once method. ideally, 1 write this:

def once(element: topnode, tpe: string,     callback: function1[event,any]): unit = {   val cb: js.function1[event, any] = { (e: event) =>     e.target.removeeventlistener(e.`type`, cb) // using cb here     callback(e)   }   tpe.split(" ").foreach(item => element.addeventlistener(item, cb)) } 

however, won't compile, because cannot use val (here cb) in right-hand-side of definition, if happens inside lambda. trying results in following compile error:

main.scala:17: error: forward reference extends on definition of value cb       e.target.removeeventlistener(e.`type`, cb) // using cb here 

there simple solution, though: use lazy val instead:

def once(element: topnode, tpe: string,     callback: function1[event,any]): unit = {   lazy val cb: js.function1[event, any] = { (e: event) =>     e.target.removeeventlistener(e.`type`, cb) // using cb here     callback(e)   }   tpe.split(" ").foreach(item => element.addeventlistener(item, cb)) } 

make sure declare cb js.function1, not function1. otherwise cb refer scala function, not js function resulting automatic conversion (which have different identities). have make sure cb refers js function.

fiddle: http://www.scala-js-fiddle.com/gist/2b848e2f01e7af522dc1