javascript - In js, which one of a++ and ++a appears first in an operation?

Question

As in the title:

var a = 1;
var b = a++ + ++a;

一开始以为b的运算过程是 b = 1 + 3；
今天听说++a的优先级要高,所以实际的运算过程是后面的++a先计算，
所以实际的过程是 b = 2 + 2;

求证一下

Answer 1

Read the documentation first: operator precedence

Obviously, post-increment has higher priority than pre-increment.
That is to say, calculate firsta++然后才是++a.

So why does this operation expression end up as 2 + 2? 2 + 2？
因为这俩运算都比+运算优先级高。
然后，虽然a++先运算，但是a自增要等到整个算式运算结束，而++a则是马上就自增。
a++和++a运算之后，+运算之前，a的值就是2。
最后整个算式运算结束，a才会自增到3Because these two operations have higher priority than the + operation.

Then, although a++ is calculated first, the increment of a has to wait until the entire calculation is completed, while ++a is incremented immediately. . 🎜After the a++ and ++a operations, but before the + operation, the value of a is 2< /code>. 🎜Finally, when the entire calculation is completed, a will increase to 3. You can print it out and take a look. 🎜