JavaScript代码在回调中不起作用

在下面的JavaScript代码中，如果warnBeforeNew为false，则文件打开代码可以工作。但是，如果warnBeforeNew为true，则不会出现错误，而是给出一个错误“UncaughtTypeError:无法读取未定义的属性“root”

我不知道这是否与作用域有关，但如何让文件加载代码在回调中工作？谢谢

Editor.prototype.open = function(path) {
  if (Editor.warnBeforeNew==true){
    this.showDialog({
        dialogLabel: 'You have unsaved changes. Are you sure you want to discard them and open a different file?',
        submitLabel: 'Discard',
        cancelLabel: 'Cancel',
        submitCallback: function() {
          Editor.warnBeforeNew=false;
          this.filesystem.root.getFile(path, {}, this.load.bind(this), error.bind(null, "getFile " + path));
        }
    });
  } else {
    this.filesystem.root.getFile(path, {}, this.load.bind(this), error.bind(null, "getFile " + path));
  }
};

---

您必须保存

this

的值，因为调用回调时，它的接收器与外部函数不同：

if (Editor.warnBeforeNew==true){
    var thing = this; // choose a more meaningful name if possible...
    this.showDialog({
        dialogLabel: 'You have unsaved changes. Are you sure you want to discard them and open a different file?',
        submitLabel: 'Discard',
        cancelLabel: 'Cancel',
        submitCallback: function() {
          Editor.warnBeforeNew=false;
          thing.filesystem.root.getFile(path, {}, thing.load.bind(thing), error.bind(null, "getFile " + path));
        }
    });
  } else {
    this.filesystem.root.getFile(path, {}, this.load.bind(this), error.bind(null, "getFile " + path));
  }

---

尝试捕捉回调之外的作用域并使用它

Editor.prototype.open = function(path) {
var that=this;
  if (Editor.warnBeforeNew==true){
    this.showDialog({
        dialogLabel: 'You have unsaved changes. Are you sure you want to discard them and open a different file?',
        submitLabel: 'Discard',
        cancelLabel: 'Cancel',
        submitCallback: function() {
          Editor.warnBeforeNew=false;
          that.filesystem.root.getFile(path, {}, that.load.bind(that), error.bind(null, "getFile " + path));
        }
    });
  } else {
    this.filesystem.root.getFile(path, {}, this.load.bind(this), error.bind(null, "getFile " + path));
  }
};

---

submitCallback

到您的

showDialog

方法也需要绑定-它访问

这个失败的.filesystem.root….

this.showDialog({
    …,
    submitCallback: function() {
      Editor.warnBeforeNew=false;
      this.filesystem.root.getFile(path, {}, this.load.bind(this), error.bind(null, "getFile " + path));
    }.bind(this)
//    ^^^^^^^^^^
});

---

你忘了在bind中将

这个
替换为
东西
你忘了将
这个
替换为
那个
其中
加载
方法是boundya你是对的
那个.filesystem.root.getFile（路径，{}，那个.load.bind（那个），error.bind（null，“getFile”+path））