Vue.js event change method does not initiate the trigger

Question

Vue.js event change method does not initiate the trigger

I have been attempting to implement a change event in my Vue application, where a statement switches between true and false each time I check a checkbox. However, the functionality doesn't seem to be working as expected.

This issue arose while following along with a tutorial that inspired me to experiment by adding this change event.

<div v-for="task in tasks" :key="task.id" v-if="task.completed">
  <ul>
  <li v-text="task.description"></li>
  <input type="checkbox" @change="changeComplete">
  </ul>
</div>




var app = new Vue ({
  el: '#root',
  data:  {
    tasks: [
           {description: 'clean room', completed: true, id: 1},
           {description: 'do homework', completed: true, id: 2},
           {description: 'go to sleep', completed: false, id: 3}
           ]
          },
  methods: {
    changeComplete() {
          this.task.completed = !this.task.completed;
          }
      }
  })

Despite expecting the completion status of a task to toggle when its checkbox is checked, the change event fails to trigger, leaving the completed value unaltered.

javascript vue.js

Answer 1

Answer №1

If there is no task property within the data object, you will need to make changes in the tasks array instead. In order to do this, you must pass an index to identify which task needs to be modified.

var app = new Vue ({
  el: '#root',
  data: {
    tasks: [
           {description: 'clean room', completed: true, id: 1},
           {description: 'do homework', completed: true, id: 2},
           {description: 'go to sleep', completed: false, id: 3}
           ]
          },
  methods: {
    changeComplete(index) {
          this.tasks[index].completed = !this.tasks[index].completed;
          }
      }
  })

<script src="https://cdnjs.cloudflare.com/ajax/libs/vue/2.6.10/vue.js"></script>
<div id="root">
<div>
<div v-for="task,index in tasks" :key="task.id" v-if="task.completed">
  <ul>
  <li v-text="task.description"></li>
  <input type="checkbox" @change="changeComplete(index)">
  </ul>
</div>
</div>
</div>

Alternatively, you can simply modify the class to switch or toggle the status of the task

var app = new Vue ({
  el: '#root',
  data: {
    tasks: [
           {description: 'clean room', completed: true, id: 1},
           {description: 'do homework', completed: true, id: 2},
           {description: 'go to sleep', completed: false, id: 3}
           ]
          },
  methods: {
    changeComplete(index) {
          this.tasks[index].completed = !this.tasks[index].completed;
          }
      }
  })

.completed{
  color: green;
  text-decoration: line-through;
}

<script src="https://cdnjs.cloudflare.com/ajax/libs/vue/2.6.10/vue.js"></script>
<div id="root">
<div>
<div :class='{completed:task.completed}' v-for="task,index in tasks" :key="task.id">
  <ul>
  <li v-text="task.description"></li>
  <input type="checkbox" @change="changeComplete(index)">
  </ul>
</div>
</div>
</div>

Answer 2

If there is no task property within the data object, you will need to make changes in the tasks array instead. In order to do this, you must pass an index to identify which task needs to be modified.

var app = new Vue ({
  el: '#root',
  data: {
    tasks: [
           {description: 'clean room', completed: true, id: 1},
           {description: 'do homework', completed: true, id: 2},
           {description: 'go to sleep', completed: false, id: 3}
           ]
          },
  methods: {
    changeComplete(index) {
          this.tasks[index].completed = !this.tasks[index].completed;
          }
      }
  })

<script src="https://cdnjs.cloudflare.com/ajax/libs/vue/2.6.10/vue.js"></script>
<div id="root">
<div>
<div v-for="task,index in tasks" :key="task.id" v-if="task.completed">
  <ul>
  <li v-text="task.description"></li>
  <input type="checkbox" @change="changeComplete(index)">
  </ul>
</div>
</div>
</div>

Alternatively, you can simply modify the class to switch or toggle the status of the task

var app = new Vue ({
  el: '#root',
  data: {
    tasks: [
           {description: 'clean room', completed: true, id: 1},
           {description: 'do homework', completed: true, id: 2},
           {description: 'go to sleep', completed: false, id: 3}
           ]
          },
  methods: {
    changeComplete(index) {
          this.tasks[index].completed = !this.tasks[index].completed;
          }
      }
  })

.completed{
  color: green;
  text-decoration: line-through;
}

<script src="https://cdnjs.cloudflare.com/ajax/libs/vue/2.6.10/vue.js"></script>
<div id="root">
<div>
<div :class='{completed:task.completed}' v-for="task,index in tasks" :key="task.id">
  <ul>
  <li v-text="task.description"></li>
  <input type="checkbox" @change="changeComplete(index)">
  </ul>
</div>
</div>
</div>

Answer 3

Answer №2

In order to complete the desired task, make sure to reference it within the callback:

@change="changeComplete(task)"

Then implement the following code:

changeComplete(task) {
    task.completed = !task.completed;
}

If your v-if statement is meant to display incomplete tasks, ensure it's checking for uncompleted ones:

v-if="task.completed == false"

Below is a functional example:

Vue.config.productionTip = false;
Vue.config.devtools = false;

var app = new Vue({
  el: '#root',
  template: '<div> \
    <div v-for="task in tasks" :key="task.id" v-if="task.completed == false"> \
      <ul> \
        <li> \
          <span v-text="task.description"></span> \
          <input type="checkbox" @change="changeComplete(task)"> \
        </li> \
      </ul> \
    </div></div>',
  
  data: {
    tasks: [{
        description: 'clean room',
        completed: false,
        id: 1
      },
      {
        description: 'do homework',
        completed: false,
        id: 2
      },
      {
        description: 'go to sleep',
        completed: false,
        id: 3
      }
    ]
  },
  methods: {
    changeComplete(task) {
      task.completed = !task.completed;
    }
  }
})

<script src="https://cdnjs.cloudflare.com/ajax/libs/vue/2.5.17/vue.js"></script>
<div id="root"></div>

Answer 4

In order to complete the desired task, make sure to reference it within the callback:

@change="changeComplete(task)"

Then implement the following code:

changeComplete(task) {
    task.completed = !task.completed;
}

If your v-if statement is meant to display incomplete tasks, ensure it's checking for uncompleted ones:

v-if="task.completed == false"

Below is a functional example:

Vue.config.productionTip = false;
Vue.config.devtools = false;

var app = new Vue({
  el: '#root',
  template: '<div> \
    <div v-for="task in tasks" :key="task.id" v-if="task.completed == false"> \
      <ul> \
        <li> \
          <span v-text="task.description"></span> \
          <input type="checkbox" @change="changeComplete(task)"> \
        </li> \
      </ul> \
    </div></div>',
  
  data: {
    tasks: [{
        description: 'clean room',
        completed: false,
        id: 1
      },
      {
        description: 'do homework',
        completed: false,
        id: 2
      },
      {
        description: 'go to sleep',
        completed: false,
        id: 3
      }
    ]
  },
  methods: {
    changeComplete(task) {
      task.completed = !task.completed;
    }
  }
})

<script src="https://cdnjs.cloudflare.com/ajax/libs/vue/2.5.17/vue.js"></script>
<div id="root"></div>

Vue.js event change method does not initiate the trigger

Answer №1

Answer №2

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