Pass selected value to vuejs function

This should work if you want to loop with dynamic values and can not use v-model

<select name="option" v-on:change="selectedOption($event.target.value)">
    <option value="0">SELECT</option>
    <option v-for="i in 10" :value="i">{{ i }}</option>
</select>

You have several ways to do it.

Edit: Improved 2)

It is possible to use v-model just like in 2) but instead of using the value directly in your orderBy filter, you can use computed properties

computed: {
    sortKey: {
        get: function() {
            return this.sorting.split(' ')[0]; // return the key part
        }
    },
    sortOrder: {
        get: function() {
            return this.sorting.split(' ')[1]; // return the order part
        }
    }
}

This way, sortKey and sortOrder will be available like a normal property in you filter:

v-repeat="items | orderBy sortKey sortOrder"

1) Use javascript event:

If you don't specify any parameter, the native event object will be passed automatically

<select class="sort-filter" v-on:change="sortBy">

You can then use it like this:

methods: {
    sortBy: function(e) {
        console.log(e.target.value);
    },
}

2) Using v-model

You can add the v-model directive

<select name="test" v-model="sorting" v-on:change="sortBy">

This way the sorting value will be updated on every change.

You can add this value in the data object of you ViewModel to be more clear:

data: {
  sorting: null // Will be updated when the select value change
}

You can then access the value like in your method:

methods: {
    sortBy: function() {
        console.log(this.sorting);
    },
}

If you just need to update the sortKey value, this method is not even necessary.

3) Other weird way

You can apparently use your model value as a parameter.

<select name="test" v-model="sortKey" v-on:change="sortBy(sortKey)">

This is working but I don't really see the point.

methods: {
    sortBy: function(sortKey) {
        console.log(sortKey);
    },
}

If you want to pass selected value to a vuejs function, Please do the following :

1. you need to use v-model directive in select tag as v-model = variableName
2. pass that variable as parameter like @on-change=sortBy(variableName);

So your code will look like :

<select class="sort-filter" v-model="sortingVariable" @on-change="sortBy(sortingVariable)"> 
   <option value="title asc">Title (A-Z)</option>
   <option value="title desc">Title (Z-A)</option>
   <option value="price asc">Price (Min. - Max.)</option>
   <option value="price desc">Price (Max. - Min.)</option>
</select>