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I'm using a third-party library that has a function that takes functions as arguments. I'm doing some conditional checks to decide whether or not to add a particular function as a parameter and in some cases I don't want to provide a function. Providing null in that cases throws an error.
I found this code which works, but I don't fully understand what's happening.
compose(__DEV__ ? devTools() : f => f) Is f => f equivalent to () => {} an empty anonymous function?
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It's a new feature that introduced in ES6 and is called arrow function. The left part denotes the input of a function and the right part the output of that function.
Anonymous Function is a function that does not have any name associated with it. Normally we use the function keyword before the function name to define a function in JavaScript, however, in anonymous functions in JavaScript, we use only the function keyword without the function name.
Anonymous functions, also known as closures , allow the creation of functions which have no specified name. They are most useful as the value of callable parameters, but they have many other uses. Anonymous functions are implemented using the Closure class. printf("Hello %s\r\n", $name);
One common use for anonymous functions is as arguments to other functions. Another common use is as a closure, for which see also the Closures chapter. Use as an argument to other functions: setTimeout(function() { alert('hello'); }, 1000);
f => f is the identity function. It simply returns the argument that was passed in.
This function is often used as a default values for transformation processes, since it doesn't perform any transformation.
Is
f => fequivalent to() => {}an empty anonymous function?
No. The empty function doesn't return anything. The identity function returns the passed in argument.
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