function addHandler()

in assets/views/vue.js [6573:6647]

• 61 lines of code
• 20 McCabe index (conditional complexity)

function addHandler (
  el,
  name,
  value,
  modifiers,
  important,
  warn
) {
  modifiers = modifiers || emptyObject;
  // warn prevent and passive modifier
  /* istanbul ignore if */
  if (
    "development" !== 'production' && warn &&
    modifiers.prevent && modifiers.passive
  ) {
    warn(
      'passive and prevent can\'t be used together. ' +
      'Passive handler can\'t prevent default event.'
    );
  }

  // check capture modifier
  if (modifiers.capture) {
    delete modifiers.capture;
    name = '!' + name; // mark the event as captured
  }
  if (modifiers.once) {
    delete modifiers.once;
    name = '~' + name; // mark the event as once
  }
  /* istanbul ignore if */
  if (modifiers.passive) {
    delete modifiers.passive;
    name = '&' + name; // mark the event as passive
  }

  // normalize click.right and click.middle since they don't actually fire
  // this is technically browser-specific, but at least for now browsers are
  // the only target envs that have right/middle clicks.
  if (name === 'click') {
    if (modifiers.right) {
      name = 'contextmenu';
      delete modifiers.right;
    } else if (modifiers.middle) {
      name = 'mouseup';
    }
  }

  var events;
  if (modifiers.native) {
    delete modifiers.native;
    events = el.nativeEvents || (el.nativeEvents = {});
  } else {
    events = el.events || (el.events = {});
  }

  var newHandler = {
    value: value.trim()
  };
  if (modifiers !== emptyObject) {
    newHandler.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;
  }

  el.plain = false;
}