Javascript Question
How to use arrow function instead of 'bind' in a helper function
I have a class, which imports a helper function
import {foo} from '../helper/foo';
...
foo(someArg, this.retFunc.bind(this));
Which works fine - I call the helper function 'foo', pass it an argument 'someArg' and it calls the retFunc with the proper context for 'this'.
Hoew would I replace the above with an arrow function? When I do the following, retFunc never gets called:
foo(someArg, () => this.retFunc);
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Answer Source
There are two issues with
foo(someArg, () => this.retFunc)
First, the callback function (() => this.retFunc) does not call the function, and will only return a function when the callback is called, which is probably not helpful in you example.
However
foo(someArg, () => this.retFunc())
has another issue, which is that any parameters passed to the callback function will be ignored, and won't be passed to this.retFunc(). This can be a good thing, or a bad thing, depending on what you expect retFunc to need for parameters.
As you're after a substitute for .bind(this) then the appropriate replacement would be to use rest parameters to pass any input to your function:
foo(someArg, (...args) => this.retFunc(...args))
All that said, you're not saving anything by attempting to replace bind in this particular example:
foo(someArg, this.retFunc.bind(this))
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