问题

My component vue is like this :

<template>
    <select class="form-control" v-model="selected" :required @change="changeLocation">
        <option :selected>Choose Province</option>
        <option v-for="option in options" v-bind:value="option.id" >{{ option.name }}</option>
    </select>
</template>

I use this : <option :selected>Choose Province</option> to selected

But whene executed, on the gulp watch exist error

The error like this :

ERROR in ./~/vue-loader/lib/template-compiler.js?id=data-v-53777228!./~/vue-load er/lib/selector.js?type=template&index=0!./resources/assets/js/components/bootst rap/LocationBsSelect.vue Module build failed: SyntaxError: Unexpected token (28:4)

Seems my step is wrong

How can I solve it?

回答1:

Handling the errors

You are binding properties to nothing. :required in

<select class="form-control" v-model="selected" :required @change="changeLocation">

and :selected in

<option :selected>Choose Province</option>

If you set the code like so, your errors should be gone:

<template>
  <select class="form-control" v-model="selected" :required @change="changeLocation">
    <option>Choose Province</option>
    <option v-for="option in options" v-bind:value="option.id" >{{ option.name }}</option>
 </select>
</template>

Getting the select tags to have a default value

you would now need to have a data property called selected so that v-model works. So,
```
{
  data () {
    return {
      selected: "Choose Province"
    }
  }
}
```

If that seems like too much work, you can also do it like:

<template>
  <select class="form-control" :required="true" @change="changeLocation">
   <option :selected="true">Choose Province</option>
   <option v-for="option in options" v-bind:value="option.id" >{{ option.name }}</option>
  </select>
</template>

When to use which method?

You can use the v-model approach if your default value depends on some data property.
You can go for the second method if your default selected value happens to be the first option.

You can also handle it programmatically by doing so:

<select class="form-control" :required="true">
  <option 
   v-for="option in options" 
   v-bind:value="option.id"
   :selected="option == '<the default value you want>'"
  >{{ option }}</option>
</select>

回答2:

The simplest answer is to set the selected option to true or false.

<option :selected="selectedDay === 1" value="1">1</option>

Where the data object is:

data() {
    return {
        selectedDay: '1',
        // [1, 2, 3, ..., 31]
        days: Array.from({ length: 31 }, (v, i) => i).slice(1)
    }
}

This is an example to set the selected month day:

<select v-model="selectedDay" style="width:10%;">
    <option v-for="day in days" :selected="selectedDay === day">{{ day }}</option>
</select>

On your data set:

{
    data() {
        selectedDay: 1,
        // [1, 2, 3, ..., 31]
        days: Array.from({ length: 31 }, (v, i) => i).slice(1)
    },
    mounted () {
        let selectedDay = new Date();
        this.selectedDay = selectedDay.getDate(); // Sets selectedDay to the today's number of the month
    }
}

回答3:

<select v-model="challan.warehouse_id">
<option value="">Select Warehouse</option>
<option v-for="warehouse in warehouses" v-bind:value="warehouse.id"  >
   {{ warehouse.name }}
</option>

Here "challan.warehouse_id" come from "challan" object you get from:

editChallan: function() {
    let that = this;
    axios.post('/api/challan_list/get_challan_data', {
    challan_id: that.challan_id
 })
 .then(function (response) {
    that.challan = response.data;
 })
 .catch(function (error) {
    that.errors = error;
  }); 
 }

回答4:

You simply need to remove v-bind (:) from selected and required attributes. Like this :-

<template>
    <select class="form-control" v-model="selected" required @change="changeLocation">
        <option selected>Choose Province</option>
        <option v-for="option in options" v-bind:value="option.id" >{{ option.name }}</option>
    </select>
</template>

You are not binding anything to the vue instance through these attributes thats why it is giving error.

来源：https://stackoverflow.com/questions/43839066/how-can-i-set-selected-option-selected-in-vue-js-2

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javascript