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Quiz Questions

What's a typical use case for anonymous functions?

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They can be used in IIFEs to encapsulate some code within a local scope so that variables declared in it do not leak to the global scope.

(function () {
// Some code here.

As a callback that is used once and does not need to be used anywhere else. The code will seem more self-contained and readable when handlers are defined right inside the code calling them, rather than having to search elsewhere to find the function body.

setTimeout(function () {
console.log('Hello world!');
}, 1000);

Arguments to functional programming constructs or Lodash (similar to callbacks).

const arr = [1, 2, 3];
const double = arr.map(function (el) {
return el * 2;
console.log(double); // [2, 4, 6]
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