如何在 Javascript 中将对象的方法作为参数传递

Question

无法弄清楚如何将对象的方法作为参数正确传递。

这是我的代码：

var MyTest = function (p1) {
  this.p1 = p1;
};
MyTest.prototype.getParam = function () {
  return this.p1;
};

function doAction(getParamCallback) {
  console.log(getParamCallback());
}

var mt = new MyTest(123);
console.log(mt.getParam()); // 123
doAction(mt.getParam);      // undefined

我发现正确传递方法的唯一方法是同时传递对象和方法并使用 call():

function doAction2(obj, getParamCallback) {
  console.log(getParamCallback.call(obj));
}
doAction2(mt, mt.getParam);    // 123

有什么方法只需要传递方法，而不是同时传递方法和对象吗？

Answer 1

You need to pass the this context as well. In provided example, methos is being called in the context of window, and window does not have property p1

Use .bind() to pass the context. bind returns a function that when later executed will have the correct context set for calling the original function. This way you can maintain context in async callbacks, and events.[Reference]

试试这个：

var MyTest = function(p1) {
  this.p1 = p1;
};
MyTest.prototype.getParam = function() {
  return this.p1;
};

function doAction(getParamCallback) {
  alert(getParamCallback());
}

var mt = new MyTest(123);

doAction(mt.getParam.bind(mt));

如何在 Javascript 中将对象的方法作为参数传递

How to pass object's method as a parameter in Javascript

javascript

function

object

parameter-passing