bind-callbacks

Bind instance methods of a class to its own object and use them around without having to resort to .bind(this).

Disclaimer

This may be considered an over-optimization technique, and thus an anti-pattern. Use at your own risk.

Usage

Consider the following ES6 class:

class Thing {
  constructor (value) {
    this.value = value
  }
  increment () {
    this.value++
  }
}

If you want to call an instance method using things like setTimeout, callbacks in general, event emitters, and so on, you have to resort to bind() like this:

var thing = new Thing(5)
setTimeout(thing.increment.bind(thing), 100)

If you don't use .bind(thing) in the code above, the value of this will be lost inside the increment() method.

However, bind() returns a new function, as stated in its documentation. This causes memory allocation, giving more work to the garbage collector later on, and increasing the chance of memory leaks.

This component provides a function that will create a callbacks property inside the object instance and then store those bound functions for your code to call later:

const bindCallbacks = require('bind-callbacks')

class Thing {
  constructor (value) {
    this.value = value
    bindCallbacks(this, 'increment') // <-- assign bound callbacks
  }
  increment () {
    this.value++
  }
}

So now you can use it like this:

var thing = new Thing(5)
setTimeout(thing.callbacks.increment, 100)

And the value of this will work as expected inside the increment() function.

License

MIT