javascript - `socket` TypeError : task is not a function - node. js async.js 上缺少错误处理程序

Question

我需要你帮助我的网络服务器控制的机器人项目。我尝试通过网站控制两个电机。

很多东西已经开始工作，所以我可以打开一个网站并按“w”键，两个电机都开始向前运行。 (我的控件:w = 向前，s = 向后，a = 向左，d = 向右)

但是另一个命令不再被处理。

在命令行上我可以看到此错误消息:

Missing error handler on `socket`.
TypeError: task is not a function
at /home/pi/tank/node_modules/async/dist/async.js:5285:13
at replenish (/home/pi/tank/node_modules/async/dist/async.js:871:21)
at /home/pi/tank/node_modules/async/dist/async.js:881:15
at _parallel (/home/pi/tank/node_modules/async/dist/async.js:5284:9)
at parallelLimit (/home/pi/tank/node_modules/async/dist/async.js:5317:14)
at Object.parallel (/home/pi/tank/node_modules/async/dist/async.js:930:20)
at Object.tank.moveForward (/home/pi/tank/app.js:46:9)
at Socket.<anonymous> (/home/pi/tank/app.js:87:9)
at emitOne (events.js:96:13)
at Socket.emit (events.js:188:7)

问题似乎出在 moveForward : function() 和 async.parallel 上(其他移动功能也有同样的问题。)

var tank = {

//we create an object with the used pins
motors : {
    leftFront: 11,
    leftBack: 12,
    rightFront: 15,
    rightBack: 16
},

//we open the gpio pins and set the as outputs
init : function(){
    gpio.open(this.motors.leftFront, "output");
    gpio.open(this.motors.leftBack, "output");
    gpio.open(this.motors.rightFront, "output");
    gpio.open(this.motors.rightBack, "output");
},

//in order to move the tank forward, we supply both motors
moveForward : function(){
    async.parallel([
    gpio.write(this.motors.leftFront, 1),
    gpio.write(this.motors.rightFront, 1)
    ])
},

//in order to move the tank backwards, we supply both motors, but with inverse polarity
moveBackward : function(){
    async.parallel([
    gpio.write(this.motors.leftBack, 1),
    gpio.write(this.motors.rightBack, 1)
    ]);
},

//in order to turn right, we supply on the left
moveLeft : function(){
    gpio.write(this.motors.leftFront, 1);
},

//in order to turn left, we supply on the right
moveRight : function(){
    gpio.write(this.motors.rightFront, 1);
},

//in order to stop both motors, we set all pins to 0 value
stop : function(){
    async.parallel([
    gpio.write(this.motors.leftFront, 0),
    gpio.write(this.motors.leftBack, 0),
    gpio.write(this.motors.rightFront, 0),
    gpio.write(this.motors.rightBack, 0)
    ]);
}
};

请帮忙!

Answer 1

您没有正确使用async.parallel()。它需要一个函数数组，并且 gpio.write() 不返回函数。

你需要做这样的事情:

var self = this;
async.parallel([
    function (callback) {
        gpio.write(self.motors.leftBack, 1, callback);
    },
    function (callback) {
        gpio.write(self.motors.rightBack, 1, callback);
    }
]);

为了避免额外的样板文件，您还可以提取一个根据需要创建必要函数的函数:

write: function (motor, value) {
    return function (callback) {
        gpio.write(motor, value, callback);
    };
},

moveForward : function(){
    async.parallel([
        this.write(this.motors.leftFront, 1),
        this.write(this.motors.rightFront, 1)
    ]);
},