JavaScript Get Function Instance with Arguments Passed In

Question

Say I have the following code.

function myFunc(item) {
    console.log(item);
}

function action() {
    return myFunc("Hello World");
}

const myUncalledFunction = action;
myUncalledFunction(); // will console.log "Hello World"

Is there a way to make this code cleaner? I've looked into .apply() but it looks like that calls the function immediately as well.

The reason I'm wanting to do this is Chai's expect for throw requires you to pass in an uncalled function. But the function I'm wanting to test requires arguments to be passed in. So currently I just created a wrapper function that returns the function with the arguments passed in.

I feel like there has to be a better way to achieve this that is cleaner and simpler for someone looking at it.

CertainPerformance · Accepted Answer · 2018-08-27 01:29:58Z

1

Use .bind to bind arguments (and a calling context, if needed) to a function, which produces a new callable function in the process. Here, you can see this as basically allowing you to pass in arguments at one time, and then call the desired function with those arguments later:

function myFunc(item) {
  console.log(item);
}
const myUncalledFunction = myFunc.bind(undefined, 'Hello World');
myUncalledFunction();

Or you might just use a concise arrow function

function myFunc(item) {
  console.log(item);
}
const myUncalledFunction = () => myFunc('Hello World');
myUncalledFunction();

answered Aug 27, 2018 at 1:29

CertainPerformance

373k55 gold badges354 silver badges359 bronze badges

Sign up to request clarification or add additional context in comments.

Collectives™ on Stack Overflow

JavaScript Get Function Instance with Arguments Passed In

1 Answer 1

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

Comments

Your Answer

Sign up or log in

Post as a guest

Related