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我用我想要的值初始化目录类的示例，但是当我试图以任何方式操作类的示例时，它返回undefined。

if (beginOfLine == 'dir') {
        let newDirectory = new directory(name); // newDirectory returns undefined
        console.log(name); // returns expected value
        console.log(newDirectory.getDirectoryName()); // returns undefined
        directories.push(newDirectory);
        newDirectory.setParent(currentDirectory);
        currentDirectory.addSubdirectory(newDirectory); 
// throws Cannot read properties of undefined (reading 'push') error 
        currentDirectory = newDirectory;
}

...

module.exports = class directory {

    directory(name) {
        this.name = name;
        this.files = []; 
        this.subdirectories = [];
        this.parent = null;
    }
    

    addSubdirectory(subdirectory) {
        this.subdirectories.push(subdirectory);
    }

    getDirectoryName() {
        return this.name;
    }

    

};