Does unary set the variable to its initial value-CodePudding

After calculating the result of this code, I wonder if the unary sets my vars as "uno" here to its original state, and if it does, how about negative unaries

let uno = 10, dos = "20", tres = 80;
console.log(  uno    dos      tres   -  uno  );

my conclusion was the equation of 103, as 11 21 81 - 10, but it's appearing not to be true!

CodePudding user response：

The unary operator has lower precedence than the increment operators. So dos is treated as (dos ). In this case, the unary operator is redundant, because the increment operator converts the value to a number first (it makes little sense to increment a string).

Since you're using the post-increment operator on dos and tres, the values of those subexpressions are the original numeric values; see javascript i vs i. So you're adding 20 and 30, not 21 and 31.

When you subtract uno at the end, this happens after the increment from uno. So the value being subtracted is 11, not 10.

The entire thing is effectively equivalent to:

let uno = 10, dos = "20", tres = 80;
let uno1 =   uno; // uno1 = 11, uno = 11
let dos1 = dos  ; // dos1 = 20, dos = 21
let tres1 = tres  ; // tres1 = 80, tres = 81
let uno2 = uno  ; // uno2 = 11, uno = 12
console.log(uno1   dos1   tres1 - uno2); // 11   20   80 - 11 = 100