Modifier to custom directive in vue

user_4830093 0
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I'm working with custom directives and want to create one such that you could use separate events for firing it based on what you pass it in the markup.

v-example-directive.mousedown="exampleFunction"
v-example-directive.mouseup="exampleFunction"
v-example-directive.click="exampleFunction"

I've looked through Vues Documentation and tried searching how to do this but have found nothing about this. Is this something that could be done such that you can create one directive and have either multiple functions inside or the ability to define what type of event you want? Or would I have to register multiple directives to achieve this?

vuejs2 vue.js
1 Answers

You can achieve this by using args or modifiers in your custom vue directive.

To use these hooks, you have to look at the binding parameter of the directive. This parameter includes a whole set of properties that you can use to bake your custom directive.

In your case, you would want to look for either the binding.modifier or binding.arg depending on the HTML structure you desire:

Argument markup: <img v-example-directive:mouseup>

Modifier markup: <img v-example-directive.mouseup>

Now that you have added a "flag", you can check for it in the directive:

Vue.directive('example-directive', {
  bind(el, binding) {
    if (binding.arg == 'mouseup') {} // Using argument markup
    if (binding.modifiers.mouseup) {} // Using modifier markup
  }
})

Example: 

Vue.directive('example-directive', {
    bind(el, binding) {
        if (binding.arg == 'mousedown') { // Check by argument given to directive
          el.addEventListener("mousedown", () => {
            binding.value() // The function provided by the directive
          });
        }else if (binding.modifiers.mouseup) { //check by modifier 
          el.addEventListener("mouseup", () => {
            binding.value()
          });
        }
    }
})

let x = new Vue({
  el:"#app",
  methods: {
    clicked() {
      console.log("clicked")
    }
  }
})
<script src="https://cdn.jsdelivr.net/npm/vue@2.5.17/dist/vue.js"></script>
<div id="app">
<button v-example-directive:mousedown="clicked">mousedown</button>
<button v-example-directive.mouseup="clicked">mouseup</button>
<!-- ... -->
</div>

user_61788320
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