How Can I Pass an Additional Argument to a Callback Function?

Passing an Additional Argument to a Callback Function

In some scenarios, it may be necessary to pass an extra argument to a callback function. This can be achieved through a simple wrapping function or arrow function.

Consider the following example:

const callWithMagic = callback => {
  const magic = getMagic();
  callback(magic);
};

Here, the callWithMagic function takes a callback function as a parameter and calls it with one argument. Suppose you have another function, processMagic, that requires two arguments: magic and theAnswer.

To pass processMagic as an argument to callWithMagic and provide an additional argument (42) to processMagic, you can create a wrapper function:

callWithMagic(function(magic) {
  return processMagic(magic, 42);
});

Alternatively, using ECMAScript 6 arrow functions, you can write:

callWithMagic(magic => processMagic(magic, 42));

Both of these approaches allow you to pass the extra argument to the processMagic function while still adhering to the signature expected by callWithMagic.

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