Error encountered in Vue3: An uncaught TypeError occurred when attempting to "set" a property called 'NewTodo' on a proxy object, as the trap function returned a falsish

Question

Error encountered in Vue3: An uncaught TypeError occurred when attempting to "set" a property called 'NewTodo' on a proxy object, as the trap function returned a falsish

I encountered an error message: Uncaught TypeError: 'set' on proxy: trap returned falsish for property 'NewTodo'

This error occurs when attempting to reset the input text value within a child component (FormAddTodo.vue).

App.vue:

export default {
  data(){
    return{
      todos: [],
      newTodo: ""
    }
  },
  components: {
    Todos,
    FormAddTodo
  }
}
</script>

<template>
  <div class="container mx-auto">
      <Todos :todos="todos" />
      <div class="py-8"></div>
      <FormAddTodo :NewTodo="newTodo" :Todos="todos" />
  </div>
</template>

FormAddTodo.vue:

<template>
    <div class="formAddTodo">
        <form @submit.prevent="handleAddTodo" class="addTodo">
            <input type="text" class="" placeholder="type new todo here..." v-model="NewTodo">
        </form>
    </div>
</template>

<script>
    export default {
        props: ['NewTodo', 'Todos'],
        methods: {
            handleAddTodo(){
                const colors = ["cyan", "blue", "indigo", "pink"]
                const todo = {
                    id: Math.random(),
                    content: this.NewTodo,
                    color: colors[Math.floor(Math.random() * ((colors.length-1) - 0 + 1) + 0)]
                }

                this.Todos.push(todo)
                this.NewTodo = '' // this line triggers the error
            }
        }
    }
</script>

javascript vue.js vuejs3

Answer 1

Answer №1

When using v-model="NewTodo", remember that NewTodo is a prop of the component.

Props should not be modified from within the child component.

Try using a different variable for the v-model and your code should work as expected.

Answer 2

When using v-model="NewTodo", remember that NewTodo is a prop of the component.

Props should not be modified from within the child component.

Try using a different variable for the v-model and your code should work as expected.

Answer 3

Answer №2

Occasionally, this issue may arise from having identical names in state, getters, and actions. In my particular situation, the conflict was between this.app (state) and app (getter). Once I adjusted the state property to this._app, the problem disappeared.

Note: The more elegant resolution for me was eliminating the getter 'app' as a solution to the issue. Getters, similar to computed properties, are beneficial only when they provide a modified variant of the state.

Answer 4

Occasionally, this issue may arise from having identical names in state, getters, and actions. In my particular situation, the conflict was between this.app (state) and app (getter). Once I adjusted the state property to this._app, the problem disappeared.

Note: The more elegant resolution for me was eliminating the getter 'app' as a solution to the issue. Getters, similar to computed properties, are beneficial only when they provide a modified variant of the state.

Answer 5

Answer №3

Dealing with various situations, I recently encountered a particular issue that may be helpful for others facing the same challenge. The error message

Uncaught TypeError: 'set' on proxy: trap returned falsish for property xxxxxx

occurs when attempting to assign a value using

this.$refs.componentName.propertyname = value;

To resolve this issue, a workaround involves utilizing a variable instead.

Here is an example:

<component-name :propertyname="variableA">

<script>
export default =  {
         components: {
              componentName,
         },    
         data() {
              variableA: 'default',
         },
         methods: {
              changeValue(){
                   this.variableA = 'I_am_a_newValue';
              },
         },
    }
</script>

Answer 6

Dealing with various situations, I recently encountered a particular issue that may be helpful for others facing the same challenge. The error message

Uncaught TypeError: 'set' on proxy: trap returned falsish for property xxxxxx

occurs when attempting to assign a value using

this.$refs.componentName.propertyname = value;

To resolve this issue, a workaround involves utilizing a variable instead.

Here is an example:

<component-name :propertyname="variableA">

<script>
export default =  {
         components: {
              componentName,
         },    
         data() {
              variableA: 'default',
         },
         methods: {
              changeValue(){
                   this.variableA = 'I_am_a_newValue';
              },
         },
    }
</script>

Answer 7

Answer №4

When updating a property on the parent, one can emit an update event:

<template>
    <div class="formAddTodo">
        <form @submit.prevent="handleAddTodo" class="addTodo">
            <input type="text" class="" placeholder="type new todo here..." v-model="NewTodo">
        </form>
    </div>
</template>

<script>
    export default {
        props: ['NewTodo', 'Todos'],
        methods: {
            handleAddTodo(){
                const colors = ["cyan", "blue", "indigo", "pink"]
                const todo = {
                    id: Math.random(),
                    content: this.NewTodo,
                    color: colors[Math.floor(Math.random() * ((colors.length-1) - 0 + 1) + 0)]
                }

                this.Todos.push(todo)
                this.$emit('update:NewTodo', ''); // this line updates NewTodo
            }
        }
    }
</script>

However, it is generally advised not to update parent properties directly as it can be expensive and lead to anti-patterns. Instead, it is recommended to use an internal variable:

<template>
    <div class="formAddTodo">
        <form @submit.prevent="handleAddTodo" class="addTodo">
            <input type="text" class="" placeholder="type new todo here..." v-model="NewTodo">
        </form>
    </div>
</template>

<script>
    export default {
        props: ['NewTodo', 'Todos'],
        data(){
          return {
             _NewTodo: this.NewTodo; //private NewTodo
          }
        },
        methods: {
            handleAddTodo(){
                const colors = ["cyan", "blue", "indigo", "pink"]
                const todo = {
                    id: Math.random(),
                    content: this.NewTodo,
                    color: colors[Math.floor(Math.random() * ((colors.length-1) - 0 + 1) + 0)]
                }

                this.Todos.push(todo);
                this._NewTodo = '';
            }
        }
    }
</script>

Answer 8

When updating a property on the parent, one can emit an update event:

<template>
    <div class="formAddTodo">
        <form @submit.prevent="handleAddTodo" class="addTodo">
            <input type="text" class="" placeholder="type new todo here..." v-model="NewTodo">
        </form>
    </div>
</template>

<script>
    export default {
        props: ['NewTodo', 'Todos'],
        methods: {
            handleAddTodo(){
                const colors = ["cyan", "blue", "indigo", "pink"]
                const todo = {
                    id: Math.random(),
                    content: this.NewTodo,
                    color: colors[Math.floor(Math.random() * ((colors.length-1) - 0 + 1) + 0)]
                }

                this.Todos.push(todo)
                this.$emit('update:NewTodo', ''); // this line updates NewTodo
            }
        }
    }
</script>

However, it is generally advised not to update parent properties directly as it can be expensive and lead to anti-patterns. Instead, it is recommended to use an internal variable:

<template>
    <div class="formAddTodo">
        <form @submit.prevent="handleAddTodo" class="addTodo">
            <input type="text" class="" placeholder="type new todo here..." v-model="NewTodo">
        </form>
    </div>
</template>

<script>
    export default {
        props: ['NewTodo', 'Todos'],
        data(){
          return {
             _NewTodo: this.NewTodo; //private NewTodo
          }
        },
        methods: {
            handleAddTodo(){
                const colors = ["cyan", "blue", "indigo", "pink"]
                const todo = {
                    id: Math.random(),
                    content: this.NewTodo,
                    color: colors[Math.floor(Math.random() * ((colors.length-1) - 0 + 1) + 0)]
                }

                this.Todos.push(todo);
                this._NewTodo = '';
            }
        }
    }
</script>

Answer 9

Answer №5

I encountered a similar issue, so for anyone else facing the same problem, here's what I did:

Make sure to check your getter and setter functions to ensure you are using the correct variables consistently throughout your code.

In my case, I was returning _tableData in the getter but modifying tableData. I had to update _tableData everywhere instead of directly modifying tableData.

Here is the code snippet that caused the issue:

get tableData(){
    return this._tableData;
}
 hideAndShowNew(event){
       let Allrecs = [...this.tableData];
            let recs = Allrecs.filter((elem) => elem.key === compareKey)[0];
recs.showFlag = true;
            Allrecs[targetIndex] = recs;
//The below line was throwing an error
             this.tableData = [...Allrecs]; 
//SOLUTION: Change tableData to _tableData
this._tableData = [...Allrecs]; 
 
    }

Answer 10

I encountered a similar issue, so for anyone else facing the same problem, here's what I did:

Make sure to check your getter and setter functions to ensure you are using the correct variables consistently throughout your code.

In my case, I was returning _tableData in the getter but modifying tableData. I had to update _tableData everywhere instead of directly modifying tableData.

Here is the code snippet that caused the issue:

get tableData(){
    return this._tableData;
}
 hideAndShowNew(event){
       let Allrecs = [...this.tableData];
            let recs = Allrecs.filter((elem) => elem.key === compareKey)[0];
recs.showFlag = true;
            Allrecs[targetIndex] = recs;
//The below line was throwing an error
             this.tableData = [...Allrecs]; 
//SOLUTION: Change tableData to _tableData
this._tableData = [...Allrecs]; 
 
    }

Error encountered in Vue3: An uncaught TypeError occurred when attempting to "set" a property called 'NewTodo' on a proxy object, as the trap function returned a falsish

Answer №1

Answer №2

Answer №3

Answer №4

Answer №5

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