Vue.js - Unable to access property 'push' as it is not defined

Question

Vue.js - Unable to access property 'push' as it is not defined

I am facing an issue with the code below that is giving me the error message

Cannot read property 'push' of undefined

:

 var vm = new Vue({
        el: '#root',
        data: {
            posts: [],
            newPost: {}
        },
        createPost: function() {
               axios.post("api/posts/create", this.newPost).then(function (response) {
                    this.posts.push(response.data);
                })
        }
 });

Upon checking the network tab in chrome dev tools, I can confirm that the response.data is indeed an object:

{
  "id": 131,
  "postContent": "<p>test</p>\n",
}

Even though the response data is an object, Can you help me understand why I am receiving this error?

javascript arrays json vue.js vuejs2

Answer 1

Answer №1

One of the reasons for this issue is that the context of this is set incorrectly, causing it to not reference the Vue component. To address this issue, you can utilize the => syntax, which provides a more elegant solution similar to assigning this self = this outside of the desired callback function.

createPost: function() {
  axios.post("api/posts/create", this.newPost).then((response) => {
     this.posts.push(response.data);
  })
}

Answer 2

One of the reasons for this issue is that the context of this is set incorrectly, causing it to not reference the Vue component. To address this issue, you can utilize the => syntax, which provides a more elegant solution similar to assigning this self = this outside of the desired callback function.

createPost: function() {
  axios.post("api/posts/create", this.newPost).then((response) => {
     this.posts.push(response.data);
  })
}

Answer 3

Answer №2

Addressing the issue mentioned by IzumiSy, it is a common problem that occurs when using axios or setTimeout function. To resolve this, you can utilize es6 arrow syntax to create a temporary local variable with vm or bind it to the function.

Using ES6

createPost: function() {
 axios.post("api/posts/create", this.newPost).then((response) => {
    this.posts.push(response.data);
 })
}

Temporary Variable Approach

createPost: function() {
let vm = this;
  axios.post("api/posts/create", this.newPost).then(function (response) {
     vm.posts.push(response.data);
  })
}

Using Binding

createPost: function() {
  axios.post("api/posts/create", this.newPost).then(function (response) {
     this.posts.push(response.data);
  }.bind(this))
}

Answer 4

Addressing the issue mentioned by IzumiSy, it is a common problem that occurs when using axios or setTimeout function. To resolve this, you can utilize es6 arrow syntax to create a temporary local variable with vm or bind it to the function.

Using ES6

createPost: function() {
 axios.post("api/posts/create", this.newPost).then((response) => {
    this.posts.push(response.data);
 })
}

Temporary Variable Approach

createPost: function() {
let vm = this;
  axios.post("api/posts/create", this.newPost).then(function (response) {
     vm.posts.push(response.data);
  })
}

Using Binding

createPost: function() {
  axios.post("api/posts/create", this.newPost).then(function (response) {
     this.posts.push(response.data);
  }.bind(this))
}

Vue.js - Unable to access property 'push' as it is not defined

Answer №1

Answer №2

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