angular style expression locals

app.html

<template>
  <button click.delegate="clickHandler1($event)"></button>
  <button click.delegate="clickHandler2(myVar, $event)"></button>
  
  <typeahead select.delegate="selectItem1($item)"></typeahead>
  <typeahead select.delegate="selectItem2(myVar, $item)"></typeahead>
</template>

app.js

import {Router} from 'aurelia-router'

export class App {
  constructor (router) {
    this.myVar = "myVar";
  }
  
  clickHandler1(event) {
  }
  
  clickHandler2(str, event) {
  }
  
  selectItem1(item) {
  }
  
  selectItem2(str, item2) {
  }
}

typeahead.js

import {Behavior} from 'aurelia-framework'

export class Typeahead {
  static metadata () {
    return Behavior
      .customElement('typeahead')
      .withProperty('select')
  }

  constructor () {
    
  }
  
  onSelect(item) {
    this.select({$item: item})
  }
}