Vue 2 arguments in inline (in-template) event handler

It is not $arguments[0], but just arguments[0] (without the $). I am surprised that it actually works in the inline handler. So the following code is valid and will work:

<component @some-event="someObject.field = arguments[0]"></component>

The docs for Methods in Inline Handlers specifies $event as a special variable that gets the first parameter passed via event. I have always used it till now.

After reading your question, a bit more research led me to this reference: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Functions/arguments

It seems every javascript function has a local variable called arguments, which is used when a function is expected to get variable number of arguments.

Using arguments[] as inline statements is definitely possible, but not documented anywhere in the context of vue.js framework. On the other hand, if you use $event in inline handler for events, it feels safer as it is documented clearly and will not break in a future version of Vue.js

Sample usage for $event:

<component @some-event="someObject.field = $event"></component>