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This article mainly introduces the application example of ES6 higher-order function, which is very detailed and has certain reference value. Friends who are interested must finish it!

Tab function

/ / here the tap function accepts a vaule and returns a closure function containing value, which is executed const tap = (value) = > (fn) = > (typeof (fn) = = 'function' & & fn (value), console.log (value)

The tab function is useful: suppose you are traversing an array from the server and find that the data is wrong, so you want to debug it to see what the array contains, you can use the tab function

[1, 2, 3, 4] .forEach ((a) = > {tap (a) ((a) = > {console.log (a)})); # 2) once function

In many cases, we only need to run the given function once, initiate a bank payment request, and so on, and the once function can be used.

Const once = (fn) = > {let done= false; return function () {return done?undefined: ((done=true), fn.apply (this,arguments))}} const doPayment = once (() = > {console.log ('payment is done')}) doPayment (); / / payment is doneconsole.log (doPayment ()); / / undefined#### 3) the application of function Corialization

When developers write code, different classes of applications write a lot of logs. We can write a log function as follows:

Const loggerHelper = (mode, initialMessage,errorMessage, lineNo) = > {if (mode = 'DEBUG') {console.debug (initialMessage,errorMessage +' at line:' + lineNo)} else if (mode = 'ERROR') {console.error (initialMessage,errorMessage +' at line:' + lineNo)} else if (mode = 'WARN') {console.warn (initialMessage,errorMessage +' at line:' + lineNo)} else throw "Wrong mode"}

When developers need to print errors in the Stats.js file to the console, they can use the following ways:

LoggerHelper ("ERROR", "ERROR At Stats.js", "Invalid argument passed", 23)

This may not be acceptable to us programmers who pursue perfect readability, so now use Curry to optimize the above code.

Let's start with a brief description of what a function is:

Corialization is the process of converting a multi-parameter function into a nested unary function.

Encapsulate a curry function that transforms a multi-parameter function into a unary function

Let curry = (fn) = > {if (typeof fn! = = 'function') {throw Error (' No function provided');} return function curriedFn (... args) {/ / whether the input parameter is less than the function argument list length, if (args.length < fn.length) {return function () {return curriedFn.apply (null, args.concat ([] .slice.call (arguments) } return fn.apply (null, args)}} let errorLogger = curry (loggerHelper) ("ERROR") ("ERROR At Stats.js"); let debugLogger = curry (loggerHelper) ("DEBUG") ("ERROR") ("Debug At Stats.js"); let warnLogger = curry (loggerHelper) ("WARN") ("Warn") ("At Stats.js") / / for error errorLogger ("Error message", 21) / / for debugging debugLogger ('Debug message', 233) / / for warning warnLogger ("Warn message", 34); this is all the content of the article "Application examples of ES6 higher-order functions". Thank you for reading! Hope to share the content to help you, more related knowledge, welcome to follow the industry information channel!

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