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no-unused-properties.md

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pageClass sidebarDepth title description since
rule-details
0
vue/no-unused-properties
disallow unused properties
v7.0.0

vue/no-unused-properties

disallow unused properties

📖 Rule Details

This rule is aimed at eliminating unused properties.

::: warning Note This rule cannot check for use of properties by other components (e.g. mixins, property access via $refs) and use in places where the scope cannot be determined. Some access to properties might be implied, for example accessing data or computed via a variable such as this[varName]. In this case, the default is to assume all properties, methods, etc. are 'used'. See the unreferencedOptions for a more strict interpretation of 'use' in these cases. :::

<!-- ✓ GOOD -->
<template>
  <div>{{ count }}</div>
</template>
<script>
export default {
  props: ['count']
}
</script>
<!-- ✗ BAD (`count` property not used) -->
<template>
  <div>{{ cnt }}</div>
</template>
<script>
export default {
  props: ['count']
}
</script>

🔧 Options

{
  "vue/no-unused-properties": ["error", {
    "groups": ["props"],
    "deepData": false,
    "ignorePublicMembers": false,
    "unreferencedOptions": []
  }]
}
  • groups (string[]) Array of groups to search for properties. Default is ["props"]. The value of the array is some of the following strings:
    • "props"
    • "data"
    • "computed"
    • "methods"
    • "setup"
  • deepData (boolean) If true, the object of the property defined in data will be searched deeply. Default is false. Include "data" in groups to use this option.
  • ignorePublicMembers (boolean) If true, members marked with a JSDoc /** @public */ tag will be ignored. Default is false.
  • unreferencedOptions (string[]) Array of access methods that should be interpreted as leaving properties unreferenced. Currently, two such methods are available: unknownMemberAsUnreferenced, and returnAsUnreferenced. See examples below.

"groups": ["props", "data"]

<!-- ✓ GOOD -->
<script>
export default {
  data() {
    return {
      count: null
    }
  },
  created() {
    this.count = 2
  }
}
</script>
<!-- ✗ BAD (`count` data not used) -->
<script>
export default {
  data() {
    return {
      count: null
    }
  },
  created() {
    this.cnt = 2
  }
}
</script>

{ "groups": ["props", "data"], "deepData": true }

<template>
  <Foo :param="state.used">
</template>
<script>
  export default {
    data() {
      return {
        state: {
          /* ✓ GOOD */
          used: null,
          /* ✗ BAD (`state.unused` data not used) */
          unused: null
        }
      }
    }
  }
</script>

"groups": ["props", "computed"]

<!-- ✓ GOOD -->
<template>
  <p>{{ reversedMessage }}</p>
</template>
<script>
export default {
  data() {
    return {
      message: 'Hello'
    }
  },
  computed: {
    reversedMessage() {
      return this.message.split('').reverse().join('')
    }
  }
}
</script>
<!-- ✗ BAD (`reversedMessage` computed property not used) -->
<template>
  <p>{{ message }}</p>
</template>
<script>
export default {
  data() {
    return {
      message: 'Hello'
    }
  },
  computed: {
    reversedMessage() {
      return this.message.split('').reverse().join('')
    }
  }
}
</script>

{ "groups": ["props", "methods"], "ignorePublicMembers": true }

<!-- ✓ GOOD -->
<template>
  <button @click="usedInTemplate()" />
</template>
<script>
export default {
  methods: {
    /* ✓ GOOD */
    usedInTemplate() {},

    /* ✓ GOOD */
    /** @public */
    publicMethod() {},

    /* ✗ BAD */
    unusedMethod() {}
  }
}
</script>

{ "groups": ["computed"], "unreferencedOptions": ["unknownMemberAsUnreferenced"] }

<template></template>
<script>
export default {
  computed: {
    one() {
      return 1
    },
    two() {
      return 2
    }
  },
  methods: {
    handler() {
      /* ✓ GOOD - explicit access to computed */
      const a = this.one
      const i = 'two'
      /* ✗ BAD - unknown access via a variable, two will be reported as unreferenced */
      return this[i]
    },
  }
}
</script>

{ "groups": ["computed"], "unreferencedOptions": ["returnAsUnreferenced"] }

<template></template>
<script>
export default {
  computed: {
    one() {
      return 1
    },
    two() {
      return 2
    }
  },
  methods: {
    handler() {
      /* ✓ GOOD - explicit access to computed */
      const a = this.one
      /* ✗ BAD - any property could be accessed by returning `this`, but two will still be reported as unreferenced */
      return this
    },
  }
}
</script>

🚀 Version

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

🔍 Implementation