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Why should not use if and for directives together on the same element in VueJS?

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It is recommended not to use v-if on the same element as v-for. Because v-for directive has a higher priority than v-if. There are two cases where developers try to use this combination,

To filter items in a list For example, if you try to filter the list using v-if tag,

<ul>

  <li

    v-for="user in users"

    v-if="user.isActive"

    :key="user.id"

  >

    {{ user.name }}

  <li>

</ul>

This can be avoided by preparing the filtered list using computed property on the initial list

computed: {

  activeUsers: function () {

    return this.users.filter(function (user) {

      return user.isActive

    })

  }

}

...... //

...... //

<ul>

  <li

    v-for="user in activeUsers"

    :key="user.id">

    {{ user.name }}

  <li>

</ul>

To avoid rendering a list if it should be hidden For example, if you try to conditionally check if the user is to be shown or hidden

<ul>

  <li

    v-for="user in users"

    v-if="shouldShowUsers"

    :key="user.id"

  >

    {{ user.name }}

  <li>

</ul>

This can be solved by moving the condition to a parent by avoiding this check for each user

<ul v-if="shouldShowUsers">

  <li

    v-for="user in users"

    :key="user.id"

  >

    {{ user.name }}

  <li>

</ul>

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asked Feb 4, 2020 in VueJS by rajeshsharma
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