Bind instance methods of a class to its own object and use them around without having to resort to .bind(this).
This may be considered an over-optimization technique, and thus an anti-pattern. Use at your own risk.
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.
MIT