Why Doesn\'t My Vue Computed Property Update When Using Arrow Functions?

Using Arrow Functions in Vue Computed Properties

In Vue, arrow functions can be used to define computed properties. However, users may encounter an issue where the color of their computed element doesn't change when using arrow functions.

Comparison of Original and Modified Code

The original code uses traditional function syntax to define computed properties:

computed: {
  switchRed: function() {
    return { red: this.turnRed };
  },
  switchGreen: function() {
    return { green: this.turnGreen };
  },
  switchBlue: function() {
    return { blue: this.turnBlue };
  }
}

After modifying the code to use arrow functions, the issue arises:

computed: {
  switchRed: () => {
    return { red: this.turnRed };
  },
  switchGreen: () => {
    return { green: this.turnGreen };
  },
  switchBlue: () => {
    return { blue: this.turnBlue };
  }
}

Root Cause

The problem lies in the use of arrow functions. Arrow functions inherit their this context from the parent, whereas traditional function syntax binds this to the Vue instance. When using arrow functions in computed properties, this is not bound to the Vue instance, leading to the failure to update the color of the computed element.

Solution

To resolve the issue, it's recommended to use traditional function syntax for computed properties. Alternatively, one can use arrow functions for methods, but it's important to explicitly bind this to the Vue instance using the bind or apply methods.

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