What are the steps to troubleshoot a Vue application?

Question

What are the steps to troubleshoot a Vue application?

I've encountered an issue with a code snippet that retrieves JSON data from a RESTful API. The code only displays the .container element and reports that the items array is empty, even though no errors are being shown. I attempted to debug the problem by using console.log to display the fetch result, so I inserted

let result = await fetch('video').then(res => res.json())

into the code. However, nothing appeared in the browser console, indicating that the async getData function may not be running. I'm puzzled by this behaviour and unsure of what could be causing it.

<template lang="pug">
.container
  .columns(v-for="n in lines")
    .column.is-3.vid(v-for='item in items')
      .panel
        p.is-marginless
         a(:href='item.videoId')
           img(:src='item.thumbnail')
        .panel.vidInfo
          .columns.hax-text-centered
            .column
              .panel-item.reddit-ups
                span {{ item.score }}
                i.fa.fa-reddit-alien.fa-2x
              .panel-item.reddit-date
                i.fa.fa-calendar.fa-2x
</template>
<script>
export default {
      name: 'main',

      data: () => ({
        items: [],
        lines: 0
      }),

      async getVideo () {
        this.items = await fetch('/video').then(res => res.json())    
        this.lines = Math.ceil(this.items.length/4)

      }
  }
  </script>

javascript asynchronous vue.js vuejs2 vue-component

Answer 1

Answer №1

Your code has a few issues that the console should warn you about.

Start by defining the data object as an ES6 Object Method Shorthand instead of using arrow functions:

data() {
  return {
    items: [],
    lines: 0
  }
}

Next, if 'getVideo' is a method, it should be placed under the methods object:

methods: {
  async getVideo () {
        this.items = await fetch('/video').then(res => res.json())    
        this.lines = Math.ceil(this.items.length/4)
  }
}

I recommend using the created hook to trigger this method, but you can choose when to trigger it (on click, instance creation, or mounting):

<script>
export default {
      name: 'main',

      data() {
        return {
          items: [],
          lines: 0
        }
      },

      methods: {
        async getVideo () {
           await fetch('/video')
              .then(res => res.json())
              .then(items => this.items = items)    
           this.lines = Math.ceil(this.items.length/4)
        }
      },

      created() {
        this.getVideo()
      }
  }
  </script>

Answer 2

Your code has a few issues that the console should warn you about.

Start by defining the data object as an ES6 Object Method Shorthand instead of using arrow functions:

data() {
  return {
    items: [],
    lines: 0
  }
}

Next, if 'getVideo' is a method, it should be placed under the methods object:

methods: {
  async getVideo () {
        this.items = await fetch('/video').then(res => res.json())    
        this.lines = Math.ceil(this.items.length/4)
  }
}

I recommend using the created hook to trigger this method, but you can choose when to trigger it (on click, instance creation, or mounting):

<script>
export default {
      name: 'main',

      data() {
        return {
          items: [],
          lines: 0
        }
      },

      methods: {
        async getVideo () {
           await fetch('/video')
              .then(res => res.json())
              .then(items => this.items = items)    
           this.lines = Math.ceil(this.items.length/4)
        }
      },

      created() {
        this.getVideo()
      }
  }
  </script>

What are the steps to troubleshoot a Vue application?

Answer №1

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