Mastering JavaScript Functional Programming - Second Edition

Working with methods

There is, however, a case that you should be aware of: what happens if you are calling an object's method? Look at the following code: 

fetch("some/remote/url").then(function(data) {  myObject.store(data);});

If your original code had been something along the lines of the preceding code, then the seemingly obvious transformed code would fail:

fetch("some/remote/url").then(myObject.store);

Why? The reason is that in the original code, the called method is bound to an object (myObject), but in the modified code, it isn't bound and is just a free function. We can then fix it in a simple way by using bind(), as follows:

fetch("some/remote/url").then(myObject.store.bind(myObject));

This is a general solution. When dealing with ...