Does utilizing this.someFunction.bind(this) serve a purpose or is it duplicative

As I analyze someone's code, I stumbled upon the following snippet:

this.device_name.changes().onValue(this.changeName.bind(this))

My interpretation so far is that onValue requires a callback function, which in this case is this.changeName.bind(this)). Am I correct in my understanding?

  • The default value of this within a function call typically points to the object upon which the function was called.
  • By using the .bind(someObject) method, the function's this will refer to someObject when executed.

Given these details, it appears that this.changeName.bind(this) might be redundant: the default this for calling this.changeName will likely match the this provided in the bind parameter.

Hence, can we simplify the function by just using this.changeName without altering its behavior?

javascript

Answer №1

The bind function is crucial in this scenario.

When a function is called, its this pointer is determined. The calling object sets the this pointer, which can be null or (in the case of DOM objects) pointing to the DOM object itself.

By using the bind function in this specific way, it creates a new function that specifically links the this reference to the value given to the bind function. Removing the bind function will completely disrupt the this pointer, resulting in a significant change in behavior.

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