Can I pass parameters in computed properties in Vu

Question

is this possible to pass parameter in computed properties in Vue.Js. I can see when having getters/setter using computed, they can take a parameter and assign it to a variable. like here from documentation:

// ...
computed: {
  fullName: {
    // getter
    get: function () {
      return this.firstName + ' ' + this.lastName
    },
    // setter
    set: function (newValue) {
      var names = newValue.split(' ')
      this.firstName = names[0]
      this.lastName = names[names.length - 1]
    }
  }
}
// ...

Is this also possible:

// ...
computed: {
  fullName: function (salut) {
      return salut + ' ' + this.firstName + ' ' + this.lastName    
  }
}
// ...

Where computed property takes a argument and returns desired output. However when I try this, I am getting this error:

vue.common.js:2250 Uncaught TypeError: fullName is not a function(…)

Should I be using methods for such cases?

Answer 1

You can pass parameters but either it is not a vue.js way or the way you are doing is wrong.

However there are cases when you need to do so.I am going to show you a simple example passing value to computed property using getter and setter.

<template>
    <div>
        Your name is {{get_name}} <!-- John Doe at the beginning -->
        <button @click="name = 'Roland'">Change it</button>
    </div>
</template>

And the script

export default {
    data: () => ({
        name: 'John Doe'
    }),
    computed:{
        get_name: {
            get () {
                return this.name
            },
            set (new_name) {
                this.name = new_name
            }
        },
    }    
}

When the button clicked we are passing to computed property the name 'Roland' and in set() we are changing the name from 'John Doe' to 'Roland'.

Below there is a common use case when computed is used with getter and setter. Say you have the follow vuex store:

export default new Vuex.Store({
  state: {
    name: 'John Doe'
  },
  getters: {
    get_name: state => state.name
  },
  mutations: {
    set_name: (state, payload) => state.name = payload
  },
})

And in your component you want to add v-model to an input but using the vuex store.

<template>
    <div>
        <input type="text" v-model="get_name">
        {{get_name}}
    </div>
</template>
<script>
export default {
    computed:{
        get_name: {
            get () {
                return this.$store.getters.get_name
            },
            set (new_name) {
                this.$store.commit('set_name', new_name)
            }
        },
    }    
}
</script>