javascript - 为每个数组元素定义一个函数

Question

我想在不编写X次代码的情况下完成此操作。你如何在 JavaScript 中做到这一点？我来自 java 。

        floors[0].on("up_button_pressed", function() { 
            elevator.goToFloor(floors[0].floorNum());
        } );
        floors[0].on("down_button_pressed", function() { 
            elevator.goToFloor(floors[0].floorNum());
        } );

        floors[1].on("up_button_pressed", function() { 
            elevator.goToFloor(floors[1].floorNum());
        } );
        floors[1].on("down_button_pressed", function() { 
            elevator.goToFloor(floors[1].floorNum());
        } );

        floors[2].on("up_button_pressed", function() { 
            elevator.goToFloor(floors[2].floorNum());
        } );
        floors[2].on("down_button_pressed", function() { 
            elevator.goToFloor(floors[2].floorNum());
        } );        

        floors[3].on("up_button_pressed", function() { 
            elevator.goToFloor(floors[3].floorNum());
        } );
        floors[3].on("down_button_pressed", function() { 
            elevator.goToFloor(floors[3].floorNum());
        } ); 

        floors[4].on("up_button_pressed", function() { 
            elevator.goToFloor(floors[4].floorNum());
        } );
        floors[4].on("down_button_pressed", function() { 
            elevator.goToFloor(floors[4].floorNum());
        } );

Answer 1

首先，在

floors[0].on("up_button_pressed", function () { 
     elevator.goToFloor(floors[0].floorNum());
});

函数内的floors[0]始终与触发事件的对象相同，因此我将其更改为使用this:

floors[0].on("up_button_pressed", function () { 
        elevator.goToFloor(this.floorNum());
});

然后，只需使用 forEach 对所有楼层执行此操作即可:

floors.forEach(function (floor) {
    floor.on("up_button_pressed", function () {
        elevator.goToFloor(this.floorNum());
    });
    // same for "down_button_pressed" here
});

由于处理函数不需要访问外部变量 floor 并使用 this，如果您愿意，您甚至可以在循环外定义它们并按名称使用它们:

function onFloorUp() {
    elevator.goToFloor(this.floorNum());
}
// same for onFloorUp

floors.forEach(function (floor) {
    floor.on("up_button_pressed", onFloorUp);
    // same for "down_button_pressed" here
});