Replicating the behavior of v-if in a custom directive is not feasible. Directives are limited to affecting the DOM element they are attached to and cannot control the rendering of vnodes. (v-if differs from a directive as it generates conditional rendering code during template compilation.)
While I recommend avoiding the following suggestions if possible, I will still provide them as they align closely with your desired functionality.
1. Implement a Global Method through Vue Prototype Extension
Utilize v-if for conditional rendering. Create a global helper method within the Vue prototype that calculates access permissions.
Vue.prototype.$access = function (param) {
// Calculate access according to requirements
// ('this' refers to the component instance where the function is called)
return ...
}
Use this method in templates like so:
<my-component v-if="$access({ param: 'param' })">
2. Define Method in Root Component Instead of Vue Prototype
This approach is similar to #1 but avoids cluttering the Vue prototype by defining the method only in the root instance:
new Vue({
el: '#app',
render: h => h(App),
methods: {
access(param) {
return ...
}
}
})
Use the method in templates like this:
<my-component v-if="$root.access({ param: 'param' })">
This way, the method's origin is better identified.
3. Explore Usage of a Global Mixin
Although not optimal, consider investigating the practicality of utilizing a global mixin.
4. Implement a Custom Component for Access Calculation
Create a custom component, preferably functional, to calculate access for specific areas in your template:
Vue.component('access', {
functional: true,
props: ['param'],
render(h, ctx) {
// Calculate access based on input props
const access = calculateAccess(ctx.props.param)
// Provide access to the default scoped slot
return ctx.scopedSlots.default(access)
}
})
Use this custom component in templates as follows:
<access :param="param" v-slot="access">
<!-- Utilize 'access' within this section -->
<div>
<my-component v-if="access"></my-component>
</div>
</access>
Since <access> is a functional component, it behaves more like a function than an actual component instance.
Although possibly excessive for your current needs, this option may be useful in complex scenarios.