Decoding the `this` Mystery in VueJS

Recently, I decided to delve into the world of VueJS starting from square one. Following their official guide has been a helpful resource, but I've hit a roadblock at this section.

One particular example in the guide caught my attention...

var app5 = new Vue({
  el: '#app-5',
  data: {
    message: 'Hello Vue.js!'
  },
  methods: {
    reverseMessage: function () {
      this.message = this.message.split('').reverse().join('')
    }
  }
})

...I found myself puzzled by how the message property is being accessed directly without referencing the data object. Isn't it supposed to be accessed as this.data.message if this pertains to the current Vue instance?

To illustrate my confusion further, consider this scenario:

({
  name: "John Doe",
  data: {
    message: "Hello World"
  },
  greet: function(){
    console.log("I am " + this.name);
    console.log("I have a message for you: " + this.data.message); //observe here
  }
}).greet();

In regular vanilla JavaScript, I'd follow a different approach to access properties. Could someone shed some light on what's happening under the hood?

Answer №1

Within the Vue framework, properties of data and methods are proxied using Proxy

Answer №2

Check out this link: Vue Data Options

According to the information provided, the data object in Vue instances will be transformed into getter/setters by Vue itself, making it reactive. This means that all properties of the data object will be directly available on the new Vue instance as getters and setters through "this".

Answer №3

this is a unique entity. During compilation (yes, it goes through compilation!), the data keyword will vanish. All attributes and functions will be encapsulated within a new object, allowing this to adhere to JavaScript standards.

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