CODEWITHSUNDEEP
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billcyz
billcyz

Reputation: 1389

Vue.js .$set is not a function

I'm trying to modify the data that stored in vuejs by using $set function. But I got this error: TypeError: app.messageBox.$set is not a function.

Here is the code about how I define app and messageBox:

app = new Vue({
    el: '#app',
    data: {
        messageBox: [{
            id: 1,
            message: 'first'
        }, {
            id: 2,
            message: 'second'
        }]
    }
});

and in another js file, I try to modify the data in messageBox:

function test() {
    app.messageBox.$set(0, {message: 'aaa'});
}

Upvotes: 12

Views: 17568

Answers (2)

tony19
tony19

Reputation: 138216

The correct syntax is Vue.set(target, index, value). When used inside component code or single-file-components, you could use the equivalent alias: this.$set(target, index, value):

Vue.set(app.messageBox, 0, { message: 'outside component' });

// or when you don't access to `Vue`:
app.$set(app.messageBox, 0, { message: 'outside component' });

// or when `this` is the Vue instance:
this.$set(this.messageBox, 0, { message: 'inside component' })


const app = new Vue({
  el: '#app',
  data() {
    return {
      messageBox: [{
        id: 1,
        message: 'first'
      }, {
        id: 2,
        message: 'second'
      }]
    };
  },
  mounted() {
    setTimeout(() => {
      this.$set(this.messageBox, 0, { message: 'inside component' })
    }, 1000)
  }
});

setTimeout(() => {
  Vue.set(app.messageBox, 0, { message: 'outside component' });
}, 2000);
<script src="https://unpkg.com/[email protected]/dist/vue.min.js"></script>

<div id="app">
  <p v-for="msgBox of messageBox">{{msgBox.message}}</p>
</div>

Upvotes: 27

FreddicMatters
FreddicMatters

Reputation: 431

This example is for update the qty of product in the array car:

 const indice = this.car.findIndex((pr) => pr.id === product.id);
                    if(indice===-1){
                        product.qty = 1
                        this.car.push(product)
                    }else{
                        //Vue no detectara cambios en el array si se actualiza por indice https://stackoverflow.com/a/59289650/16988223
                        //this.car[indice].qty++
                        const productUpdated = product 
                        productUpdated.qty++
                        this.$set(this.car, indice, productUpdated)
                    }

Upvotes: 0

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