javascript - 尽管 super 调用， super 类属性仍未定义

Question

我正在尝试使用 ECMAScript 6 编写一个文本冒险游戏，并使用 Babel 转换为 ECMAScript 5。我遇到了一个奇怪的情况，它没有出现在我的代码中的其他地方。

我有一个通用操作类，它解析命令，确定给定输入是否与触发操作的命令匹配，然后调用函数来实际执行操作。

/**
 * An action represents a mapping between a string and some kind of action in
 * the system.
 */
export class Action {
    /**
     * Construct a new action instance.
     */
    constuctor () {
        this.commands = [];
    }
    /**
     * Add a command as a trigger for this action.
     *
     * @param {String} command The command string to add as a trigger.
     *
     * @returns {Boolean} True if the command was added, false otherwise.
     */
    addCommand (command) {
        var paramRegex = /\{([a-zA-Z0-9_]+)\}/g;
        var i = 0;
        var regexResult;
        var commandRegex;
        var parameters;
        if (typeof command !== 'string' || command.length < 1) {
            return false;
        }
        parameters = {};
        // Make spaces generic
        commandRegex = command.replace(/\w+/g, '\\w+');
        regexResult = paramRegex.exec(commandRegex);
        while (regexResult) {
            parameters[i] = regexResult[1];
            commandRegex = commandRegex.replace(regexResult[0], '([^\\w]+)');
            i++;
            regexResult = paramRegex.exec(commandRegex);
        }
        this.commands.push({
            regex: new RegExp(commandRegex, 'gi'),
            parameters: parameters
        });
        return true;
    }
    /**
     * Determine if the action has a trigger matching the given command string.
     *
     * @param {String} command The command to parse.
     *
     * @returns {Boolean} True if the command triggers the action, false
     * otherwise.
     */
    isTrigger (command) {
        var i;
        for (i = 0; i < this.commands.length; i++) {
            if (this.commands[i].regex.test(command)) {
                return true;
            }
        }
        return false;
    }
    /**
     * Trigger the action using the given command. This method checks if the
     * command is a trigger for the action, extracts any arguments from the
     * command string, and passes them to the {@link Action#execute} function
     * using {@link Function#apply}.
     *
     * @param {String} command The command to use to trigger the action.
     *
     * @returns {Boolean} True if the trigger was successful, false otherwise.
     */
    trigger (command) {
        var args;
        var result;
        var i;
        for (i = 0; i < this.commands.length; i++) {
            result = this.commands[i].regex.exec(command);
            if (result != null) {
                break;
            }
        }
        if (result == null) {
            return false;
        }
        args = [];
        for (i = 1; i < result.length; i++) {
            args.push(result[i]);
        }
        this.execute.apply(this, args);
    }
    /**
     * Execute the action with the given arguments.
     *
     * @returns {Boolean} True if the execution was successful, false otherwise.
     *
     * @virtual
     */
    execute () {
        throw new Error('Not implemented');
    }
}

我有一个子类，它应该实现移动 Action 并将玩家从一个位置移动到另一个位置。

/**
 * An action that moves the player.
 *
 * @extends {Action}
 */
export class MoveAction extends Action {
    constructor () {
        super();

        this.addCommand('go to {place}');
        this.addCommand('move to {place}');
        this.addCommand('go {place}');
    }
    execute (place) {
        var loc = GameObject.getGameObject(place);
        if (!loc) {
            return false;
        }
        return player.setLocation(loc);
    }
}

我已经在我的代码上运行 Babel 以生成兼容的 ECMAScript 5 代码，并尝试通过 Node.JS 手动运行它们以验证它们的工作情况，然后再将它们推送到我的 Git 存储库(我计划稍后编写测试用例)。

不过，我遇到了一个问题，Node.JS 提示 this.commands 未定义。

> var MoveAction = require('./compiled/actions/moveAction').MoveAction;
undefined
> var act = new MoveAction();
TypeError: Cannot read property 'push' of undefined
    at MoveAction.addCommand (compiled\action.js:64:26)
    at new MoveAction (compiled\actions\moveAction.js:41:39)
    at repl:1:11
    at REPLServer.defaultEval (repl.js:248:27)
    at bound (domain.js:280:14)
    at REPLServer.runBound [as eval] (domain.js:293:12)
    at REPLServer.<anonymous> (repl.js:412:12)
    at emitOne (events.js:82:20)
    at REPLServer.emit (events.js:169:7)
    at REPLServer.Interface._onLine (readline.js:210:10)

我无法立即发现我所写的内容有任何问题，并且我在当前代码的其他地方做了类似的事情，没有任何问题。我将继续研究它，看看我是否可以自己解决这个问题，但如果有人提出可以节省我时间的建议，我将不胜感激。

Answer 1

解决了，我将constructor拼写为constructor。