one confused question

[miaomiaoji]

I love your book so much,it's not only broad also deep,make me think a lot and less confusion.I also preview the 7edition on oreilly,It's also great.I can't wait to own one.But it seems to be take a long time to buy in China.

I have a question to consult you.

var a = {n: 1};
var b = a;
a.x = a = {n: 2};
console.log(a.x);
console.log(b.x);

it is a interview question from internet,and there is a lot of explanations about how to get the result.Most of them just can't convince me.
I have read several times about operator precedence ,order of evaluation part from "the definitive guide", I'm so stuck.

obviously,the key is the third line.
one explanation is "a.x" uses member access(high precedence),so it will evaluate first,it is why "b"and"a" become{n:1;x:undefined},
then the assigment, it has right-to-left associativity,make "a" become a new object{n:2},then assign {n:2} to a.x
Another explanation is order of evaluation,subexpressions will evaluate left-to-right,so "a.x" will evaluate first。

I want to ask some questions

• the reason about why "a.x" evaluate first,the above explanations are all right?the interpreter(compiler) will use two rules to decide?
• what happened when "a.x" evaluating?I found something about property accessor ,it says left-hand operand produces a reference,is this mean a new reference which equals to "a.x" ,ecma-262.

maybe it's just because my shortcoming of compiler and interpreter,I really need someone help me .
Thank you!I'm looking forward to your reply.