Can Arrow Functions Permanently Bind Class Methods in ES6?

How to Permanently Bind Class Functions Using Arrow Functions in ES6 Classes

ES6 classes provide a more concise way to write object-oriented JavaScript code. However, when it comes to defining class methods, developers may wonder if it's possible to permanently bind the method to the class instance using arrow functions, similar to what can be done with CoffeeScript.

Problem:

Traditionally, class methods are bound to the instance using the bind() method within the constructor. However, using arrow functions introduces syntactic differences that require a modified approach.

Syntax:

To bind a class function as a class instance method using an arrow function, the following syntax can be used:

class SomeClass extends React.Component {
  handleInputChange = (val) => {
    console.log('selectionMade: ', val);
  }
}

Note the difference:

Compared to the traditional approach, the arrow function requires an equal sign (=) after the property name.

Experimental Feature:

This feature is currently considered experimental in Babel. To use it, the transform-class-properties plugin must be enabled. This can be done by adding it to the plugins section of the Babel configuration file:

{
  "plugins": [
    "transform-class-properties"
  ]
}

Usage Example:

Once the feature is enabled, developers can pass the class method as a callback function and it will be scoped to the class instance, rather than the window object. For example, the following code would log the value of 'val' from within the SomeClass instance:

setTimeout(SomeClass.handleInputChange, 1000, 'foo');

Conclusion:

By leveraging arrow functions and enabling the transform-class-properties plugin, developers can permanently bind class methods to class instances. This approach simplifies the binding process and provides a concise and consistent syntax for defining class methods in ES6.

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