What does this mean? Why do you sometimes need bind

The preface

If you’re learning JavaScript, you might wonder what “this” means and why you need to bind sometimes and sometimes you don’t. Here are a few brief examples to help you sort things out.

What exactly does this mean?

1. This ==> is the name of a normal function.

2. Arrow function this ==> this is who in the environment (unchanged: current scope)

Here’s another example: inside document

2. Bind in functions

1. Specify the value of this directly in the function to prevent changes

If you specify an event to execute a function that changes this in the class, you can use bind without having to apply a layer of methods.

Directly bind the value of this at runtime.

2. The arrow function has a higher priority than bind