Question

我将类或var对象中的函数作为参数传递给另一个函数。从类中接收函数的函数执行该函数。它可以正常工作，但是类的功能从类中调用另一个函数。控制台输出错误，即类函数中调用的函数未定义。

以下可能会更好地说明

//the class variable in someClass.js
function(params...){
  getSomethingInClass: function(){
     // return some variable
  }

  functionThatIsPassed: function(arg){
    var theCalledFunction = getSomethingInClass();
    //do something with theCalledFunction
  }
}

//SOME WHERE ELSE in another function in another file
OtherFunction: function(){
//someClass is a variable being used here
  FunctionThatTakesFunction(this.someClassVar.functionThatIsPassed);
}


//FunctionThatTakesFunction is implemented in another file
FunctionThatTakesFunction(callbackFun){
  callbackFun(someArg);
}

如果我将其更改为传递整个对象someClass对象，则上述操作将起作用。传递对象是一种糟糕的编程习惯，因为FunctionThatTakesFunction需要知道其参数的功能例如

//THIS WORKS!
//other stuff is same 

//SOME WHERE ELSE in another function in another file
OtherFunction: function(){
//someClass is a variable being used here
  FunctionThatTakesFunction(this.someClassVar);
}


//FunctionThatTakesFunction is implemented in another file
FunctionThatTakesFunction(object){
  object.functionThatIsPassed(someArg);
}

Answer 1

以下是将函数传递给另一个函数的一些示例:(小提琴：http://jsfiddle.net/FvyUQ/4/）

function Cat() {
  this.myMeow = 'Mrrow';

  this.scratch = function() {
    console.log('Scritchey-scratch.');
  }
}

Cat.prototype.meow = function() {
  console.log(this.myMeow);
}

Cat.prototype.jump = function() {
  console.log('The cat jumped and said ' + this.myMeow + '!');
}

function test(fn) {
  fn();
}

function callPrototype(fn, context) {
  fn.call(context);
}

var myCat = new Cat();

test(myCat.scratch);
test(myCat.meow);
test(myCat.jump);
test(Cat.prototype.jump);
callPrototype(Cat.prototype.jump, myCat);

Answer 2

我使用闭包：

class Sample() {
    constructor() {
        this.id = 'Sample';
    }

    method(text) {
        console.log(this.id + text)
    }

    getMethod() {
        const ref = this;
        return function(text) {
            ref.method(text);
        }
    }
}

其他地方：

someFunc() {
    const sample = new Sample();
    useFunc(sample.getMethod());
}

useFunc(func) {
    func('HI');
}

输出：样本HI

javascript在需要该类对象中的另一个函数的类中传递函数

2 个答案: