no-dupe-v-else-if.md

pageClass	sidebarDepth	title	description	since
rule-details	0	vue/no-dupe-v-else-if	disallow duplicate conditions in `v-if` / `v-else-if` chains	v7.0.0

vue/no-dupe-v-else-if

disallow duplicate conditions in v-if / v-else-if chains

• ⚙️ This rule is included in all of "plugin:vue/vue3-essential", "plugin:vue/essential", "plugin:vue/vue3-strongly-recommended", "plugin:vue/strongly-recommended", "plugin:vue/vue3-recommended" and "plugin:vue/recommended".

📖 Rule Details

This rule disallows duplicate conditions in the same v-if / v-else-if chain.

<template>
  <!-- ✗ BAD -->
  <div v-if="isSomething(x)" />
  <div v-else-if="isSomething(x)" />

  <div v-if="a" />
  <div v-else-if="b" />
  <div v-else-if="c && d" />
  <div v-else-if="c && d" />

  <div v-if="n === 1" />
  <div v-else-if="n === 2" />
  <div v-else-if="n === 3" />
  <div v-else-if="n === 2" />
  <div v-else-if="n === 5" />

  <!-- ✓ GOOD -->
  <div v-if="isSomething(x)" />
  <div v-else-if="isSomethingElse(x)" />

  <div v-if="a" />
  <div v-else-if="b" />
  <div v-else-if="c && d" />
  <div v-else-if="c && e" />

  <div v-if="n === 1" />
  <div v-else-if="n === 2" />
  <div v-else-if="n === 3" />
  <div v-else-if="n === 4" />
  <div v-else-if="n === 5" />
</template>

This rule can also detect some cases where the conditions are not identical, but the branch can never execute due to the logic of || and && operators.

<template>
  <!-- ✗ BAD -->
  <div v-if="a || b" />
  <div v-else-if="a" />

  <div v-if="a" />
  <div v-else-if="b" />
  <div v-else-if="a || b" />

  <div v-if="a" />
  <div v-else-if="a && b" />

  <div v-if="a && b" />
  <div v-else-if="a && b && c" />

  <div v-if="a || b" />
  <div v-else-if="b && c" />

  <div v-if="a" />
  <div v-else-if="b && c" />
  <div v-else-if="d && (c && e && b || a)" />
</template>

🔧 Options

Nothing.

👫 Related Rules

• no-dupe-else-if

🚀 Version

This rule was introduced in eslint-plugin-vue v7.0.0

🔍 Implementation

• Rule source
• Test source