Function addHandler

static/vuejs/vue.esm.js:5473–5506

(
  el,
  name,
  value,
  modifiers,
  important
)

}

function addHandler (
  el,
  name,
  value,
  modifiers,
  important
) {
  // check capture modifier
  if (modifiers && modifiers.capture) {
    delete modifiers.capture;
    name = '!' + name; // mark the event as captured
  }
  if (modifiers && modifiers.once) {
    delete modifiers.once;
    name = '~' + name; // mark the event as once
  }
  var events;
  if (modifiers && modifiers.native) {
    delete modifiers.native;
    events = el.nativeEvents || (el.nativeEvents = {});
  } else {
    events = el.events || (el.events = {});
  }
  var newHandler = { value: value, modifiers: modifiers };
  var handlers = events[name];
  /* istanbul ignore if */
  if (Array.isArray(handlers)) {
    important ? handlers.unshift(newHandler) : handlers.push(newHandler);
  } else if (handlers) {
    events[name] = important ? [newHandler, handlers] : [handlers, newHandler];
  } else {
    events[name] = newHandler;
  }
}

function getBindingAttr (
  el,