Vuejs: how to loop start time to multiply end time with var x

Question

I have data start_time, end_time, x, and result. I want to display it in the select option, the first option is the initial data start_time, and continues to loop multiples of variable x and ends until the value is equal to end_time. here are the expectations.

Here my view:

<select class="form-control">
    <option>08:00:00</option>
    <option>08:15:00</option>
    <option>08:30:00</option>
    <option>08:45:00</option>
    <option>09:00:00</option>
    <option>...</option>
    <option>19:00:00</option>
</select>

This is my code:

data: function () {
    return {
        start_time: '08:00:00',
        end_time: '19:00:00',
        x: 15,
        result:'',
    }
},
computed:{
}

Answer 1

What you can do is create a computed property which returns an array of all the available time options given the start_time and the end_time constraints. Then loop it to your <option/> element using v-for.

  <select class="form-control">
    <option v-for="(time, index) in times" :key="index">{{time}}</option>
  </select>

computed: {
  times() {
    // transform the start_time and end_time to Date for easier comparison.
    let startTime = new Date(`1/1/1970 ${this.start_time}`);
    const endTime = new Date(`1/1/1970 ${this.end_time}`);

    // This interval is in Minutes.
    const interval = this.x * 60000;

    // The result array where we will store the time
    const results = [];

    while (startTime.getTime() <= endTime.getTime()) {
      results.push(`${this.formatTime(startTime)}`);
      startTime = new Date(startTime.getTime() + interval);
    }

    return results;
  }
},
methods: {
  formatTime(date) {
    // format the date here...
    return '00:00:00';
  }
}

For formatting date, you can either use third-party library to do the job, or you can use vanilla javascript.

formatTime(date) {
  const hours = date.getHours().toString().padStart(2, "0");
  const minutes = date.getMinutes().toString().padStart(2, "0");
  const seconds = date.getSeconds().toString().padStart(2, "0");
  return `${hours}:${minutes}:${seconds}`;
}

Here is a working demo.