JavaScript中的依赖注入不起作用

Question

I want to write a function createCoffee that accepts a function argument called knowHow

    function createCoffee(knowHow){
var x=new knowHow(coffee,beans,milk,sugar);
knowHow.create();
}

This is so that I can have different knowHow for how to create the coffee.

Then I write a sample knowHow function

    var x=function oneWay(a,b,c,d){
console.log(a+b+c+d)
};

I pass x to createCoffee

Then

a=5;b=1;c=2;d=2;

createCoffee(x);

This should createCoffee according to the specified knowHow.

I expected that the result would be logging in the sum of the variables. Does it have something to do with variable scope.

Is the example logically sound. How can I specify the variables in the oneWay(...) function

Answer 1

而不是初始化a，b，c，d，这样做：

var coffee=5, beans=1, milk=2, sugar=2;

Answer 2

Thanks everyone. I solved my objective in the following way ....

function coffeeMaker(knowHow,coffee,milk,sugar){
    knowHow.create(coffee,milk,sugar);
}

var x={create: function oneWay(a,b,c){
    console.log(a+b+c);
}};

coffeeMaker(x,2,3,4);

I wanted to make it so that I could do the program according to interface thing as is done in Java.

In Java you can pass reference to an interface and you can have different implementations. I wanted to achieve the same thing.

In this I can change the knowHow and plug it into the coffeeMaker.

It looks redundant in the present case but when there are like 10 behaviors associated with an object then it becomes useful. I am drawing on the Strategy design pattern for this.