赋值操作总是从右到左复制数据？

Question

看看这个Javascript代码:

var myString = new String();
myString.myObject = "myObject...";

//works fine as it shows "myObject..."
console.log("myString.myObject        :" + myString.myObject);
//OK myObject is also a string so it should give length and it works fine
console.log("myString.myObject.length :" + myString.myObject.length);
//it should not give anything or undefined since nothing is given to myString
console.log("myString                 :" + myString);
//myString is not yet defined so it should give undefined or 0..
console.log("myString.length          :" + myString.length);

//lets make a simple assignment
myString = myString.myObject;
//it should just copy value of myObject to myString so there are two copies of string "myObject.."

//lets log all the data all the data as i did above

console.log("myString.myObject        :" + myString.myObject);

//and this part is giving error
//console.log("myString.myObject.length :" + myString.myObject.length);

console.log("myString                 :" + myString);
console.log("myString.length          :" + myString.length);

在上半部分(在分配之前),它正如我预期的那样工作,但是在分配之后它会产生错误.

它似乎myString.myObject在分配后被删除.是吗？.

当我尝试访问myString.myObject控制台时出现红色错误.分配是否删除myString.myObject,或其他事情在这里发生？

Answer 1

当你这样做

myString = myString.myObject;

你myString用它的myObject属性值替换整个值.因为它本身没有myObject属性,所以在myString分配后你没有属性.

这个任务后,该值myString是"myObject...".