将额外的参数传递给回调函数

Question

我有一个函数callWithMagic，它接受一个回调函数作为参数并用一个参数调用它。

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

我还有一个函数 processMagic，它接受两个参数：magic 和 theAnswer。

const processMagic = (magic, theAnswer) => {
  someOtherMagic();
};

我想将函数processMagic 作为参数传递给callWithMagic，但我也想将42 作为第二个参数（theAnswer）传递给processMagic。我该怎么做？

callWithMagic(<what should I put here?>);

Answer 1

只需创建一个function(magic) {} 作为包装回调：

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

或者使用ECMAScript 6: arrow functions:

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

Answer 2

你可以使用匿名函数

类似

session.sub('Hello', function(){marketEvents(your args);});

Answer 3

您可以创建一个调用marketEvent 函数的函数。不需要把事情复杂化

session.sub('Hello', function(args, kwargs) {
    marketEvent(args, kwargs, 'my custom data');
});

否则你可以这样做：

var mrktEvent = function(customArgs) {
    return function(args, kwargs) { 
        marketEvent(args, kwargs, customArgs) 
    };
}

session.sub('Hello', mrktEvent("customEvent"));

Answer 4

您可以将参数对象绑定到回调函数：

var varObject = {var1: "findButton", var2: true};

function cbFunc() {
    console.log(this.var1+ ":" + this.var2);
}

//Example callback
datatable.ajax.reload(cbFunc.bind(varObject));

Answer 5

我想将函数processMagic 作为参数传递给callWithMagic，但我也想将42 作为第二个参数theAnswer 传递给processMagic。我该怎么做？

好的，首先，您的实现几乎接近答案。你想这样调用你的函数callWithMagic(<what should I put here?>);。

因此，callWithMagic(<what should I put here?>); 应替换为 callWithMagic(processMagic, 42);，其中第一个参数是 callback 函数，另一个是您要添加的额外参数。

为了能够使用额外参数调用此函数，我们需要修改callWithMagic 的实现，通过定义一个新参数answer，如下所示：

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

现在，您的实现有了一个有效的 sn-p：

const spells = ["Accio", "Aguamenti", "Alohomora", "Aparecium", "Avada Kedavra", "Avifors", "Avis", "Bombarda", "Colloportus", "Confringo", "Confundus", "Crucio", "Deletrius", "Densaugeo", "Diffindo", "Dissendium", "Engorgio", "Episkey", "Evanesco", "Expecto Patronum", "Expelliarmus", "Fera Verto", "Ferula", "Fidelius", "Finite Incantatem", "Flagrate", "Flipendo", "Furnunculus", "Geminio", "Homorphus", "Immobulus", "Impedimenta", "Imperio", "Impervius", "Incarcerous", "Incendio", "Legilimens", "Levicorpus", "Liberacorpus", "Locomotor Mortis", "Lumos", "Mobiliarbus", "Mobilicorpus", "Morsmordre", "Muffliato", "Nox", "Obliviate", "Orchideous", "Petrificus Totalus", "Prior Incantato", "Protego", "Reducio", "Reducto", "Relashio", "Rennervate", "Reparo", "Repello", "Repello Muggletum", "Revelio", "Rictusempra", "Riddikulus", "Salvio Hexia", "Scourgify", "Sectumsempra", "Serpensortia", "Silencio", "Sonorus", "Stupefy", "Tarantallegra", "Tergeo", "Waddiwasi", "Wingardium Leviosa"];
const len = spells.length;

function random(max) {
  return Math.floor(Math.random() * max);
}

const getMagic = () => {
  return spells[random(len)];
}

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

const someOtherMagic = (magic, theAnswer) => {
  console.log({
    magic,
    theAnswer
  })
};

const processMagic = (magic, theAnswer) => {
  someOtherMagic(magic, theAnswer);
};

callWithMagic(processMagic, 42);