Question

我尝试循环的数组在下面的对象中称为commands。我给它了一系列命令，我在下面的函数中定义了这些命令。我的for循环位于名为commandsArray()的底部函数中。我尝试在程序中调用commandsArray()来执行数组循环，但它不起作用。

我不确定我做错了什么。我肯定想在这里使用for循环，并尝试尽可能地工作。我是Javascript的新手。

     var myRover = {
     position: [[0],[0]],
     direction: 'N',
     roverDirections: ['N', 'E', 'S', 'W'],
     marsGrid: [[0], [0]],
     obstacles: [],
     commands: ['f','f', 'f', 'r', 'f', 'f', 'l', 'f', 'f', 'f', 'b', 'b']
    };

    // MOVE FORWARD & BACKWARD COMMANDS

    function move(command) {


    if (command === 'f') {   //FORWARD

    switch(myRover.direction) {
    case 'N':
      myRover.position[0]++;
      break;
    case 'E':
      myRover.position[1]++;
      break;
    case 'S':
      myRover.position[0]--;
      break;
    case 'W':
      myRover.position[1]--;
      break;
      }
    }

    else if (command === 'b') {  //BACKWARD

        switch(myRover.direction) {
      case 'N':
        myRover.position[0]--;
        break;
      case 'E':
        myRover.position[1]--;
        break;
      case 'S':
        myRover.position[0]++;
        break;
      case 'W':
        myRover.position[1]++;
        break;

        }
       }
       return myRover.position;
      }



    // TURN COMMANDS

    function turn(command){

    if (command === 'l') {   //TURNING LEFT

      switch (myRover.direction) {
        case 'N':
        myRover.direction = 'W';
        break;
        case 'E':
        myRover.direction = 'N';
        break;
        case 'S':
        myRover.direction = 'E';
        break;
        case 'W':
        myRover.direction = 'S';
        break;
      }
    }

    if (command === "r") {    //TURNING RIGHT
      switch (myRover.direction) {
        case 'N':
        myRover.direction = 'E';
        break;
        case 'E':
        myRover.direction = 'S';
        break;
        case 'S':
        myRover.direction = 'W';
        break;
        case 'W':
        myRover.direction = 'N';
        break;
    }
}
     return myRover.direction;



}





    // Executing on a Series of Commands From the Commands Array

    function commandsArray() {


    var commandsLength = myRover.commands.length;
    for (var i = 0; i <= commandsLength; i++) {
        if (commandsLength[i] === 'f') {
          move('f');
        }

        else if (commandsLength[i] === 'b') {
          move('b');
        }

        if (commandsLength[i] === 'r') {
          turn('r');
        }
        else if (commandsLength[i] === 'l') {
          turn('l');
        }

      return myRover.position;
    }

Answer 1

从这段代码：

function commandsArray() {

    var commandsLength = myRover.commands.length;
    for (var i = 0; i <= commandsLength; i++) {
        if (commandsLength[i] === 'f') {
          move('f');
        }

        else if (commandsLength[i] === 'b') {
          move('b');
        }

        if (commandsLength[i] === 'r') {
          turn('r');
        }
        else if (commandsLength[i] === 'l') {
          turn('l');
        }

      return myRover.position;
    }
}

看起来return myRover.position位于for循环中。 myRover.commands包含数组（不是commandsLength）。试试这个：

function commandsArray() {

    var commandsLength = myRover.commands.length;
    for (var i = 0; i <= commandsLength; i++) {
        if (myRover.commands[i] === 'f') {
          move('f');
        }

        else if (myRover.commands[i] === 'b') {
          move('b');
        }

        if (myRover.commands[i] === 'r') {
          turn('r');
        }
        else if (myRover.commands[i] === 'l') {
          turn('l');
        }
    }
    return myRover.position;
}

或者更好：

function commandsArray() {
    const turns = ['l', 'r'];
    myRover.commands.forEach(command => {
       if (turns.includes(command)) {
           turn(command);
       } else {
           move(command);
       }
    });
    return myRover.position;
}

如何使用for循环遍历Javascript数组中的项目，在移动到下一个项目之前单独执行每个项目（直到完成）？

1 个答案: