如果你想让 this 属性保持一致，你应该绑定被调用的函数.

If you want to have the this property be consistent, you should bind the functions that are being called.

例如

setInterval(function() {/* code here */}.bind(this), 500)

这样，内部函数的this将与外部函数的this相同.

That way, the this of the inner function will be the same as that of the outer function.