Difference between v-on:click=“…” and using onclick=“…” in Vue.js

Question

What is the difference between v-on:click="..." and using onclick="..." in Vue.js?

I understand that with the v-on:click you need to write the handler inside of the Vue object (like the example in the docs), but what is the advantage? It seems simple enough to just write an onclick="..." to call function (outside of the Vue object).

@VicJordan unless I'm mistaken, the OP is asking about the difference between v-on and the native DOM API's onclick. The post you linked is not about that. — zero298
@VicJordan I don't think its a duplicate, the referenced question explains the sytactic shorthand — collapsar
Two reasons come to my mind: 1.) consistency - v-on: notation can be used not just for native DOM events but for application-defined vue events, thus you gain consistency. 2.) v-on: handlers can be defined not just on DOM nodes but on vue components. — collapsar
@collapsar I think I'm starting to get it. You can handle special stuff such as v-on:click.self='...'. And all your functions will have to be defined within the Vue class, thus organization. Although wouldn't your Vue class become huge? Also, this section helped me understand a bit vuejs.org/v2/guide/events.html#Why-Listeners-in-HTML — CoderSteve

zero298 zero298 · Accepted Answer · 2018-07-19T14:21:13

One of the chief differences is scope access. onclick's bound scope is global so the functions that you want it to call have to be accessible from the global scope. v-on's scope is the Vue model.

Another thing is that Vue provides a very easy API to define custom events through vm.$emit(). It's also very easy to listen for those events using v-on:customevent="callback" which can be easily cognitively mapped to a hypothetical onfizz="callback()".

With that in mind, it makes sense to also provide v-on:click for a consistent API as well as the other extensions v-on provides.

/*
 * This pollutes scope.  You would have to start
 * making very verbose function names or namespace your 
 * callbacks so as not collide with other handlers that
 * you need throughout your application.
 */
function onClickGlobal() {
  console.log("global");
}

const fizzbuzz = {
  template: "<button @click='onClick'>FizzBuzz</button>",
  methods: {
    onClick() {
      this.$emit("fizz");
    }
  }
};

const app = new Vue({
  el: "#app",
  components: {
    fizzbuzz
  },
  methods: {
    onClickModel() {
      console.log("model");
    },
    onFizz() {
      console.log("heard fizz");
    }
  }
});

<script src="https://cdn.jsdelivr.net/npm/vue/dist/vue.min.js"></script>

<div id="app">
  <section>
    <h2>Buttons and Clicks</h2>

    <!-- Calling function of the bound scope -->
    <button @click="onClickModel">v-on Model</button>
    <!-- Works as well, but calls the global  -->
    <button @click="onClickGlobal">v-on Global</button>

    <!-- You need to explicitly invoke the function from onclick -->

    <!-- This won't work because onClickModel isn't global -->
    <button onclick="onClickModel()">onclick Model</button>
    <!-- Works because onClickGlobal is global -->
    <button onclick="onClickGlobal()">onclick Global</button>

    <!-- You can technically call onClickModel through the global app -->
    <!-- but you really shouldn't -->

    <!-- Works because app.onClickModel is technically global -->
    <button onclick="app.onClickModel()">onclick Global through app.onClickModel</button>

  </section>
  <section>
    <h2>Custom Events</h2>
    <fizzbuzz @fizz="onFizz"></fizzbuzz>
    <!-- The element below doesn't work -->
    <button onfizz="onClickGlobal">Hypothetical Fizz</button>
  </section>
</div>

Difference between v-on:click=“…” and using onclick=“…” in Vue.js

2 Answers