let b = { a: 123123123 };
try {
  ({ a } = b); <<< what is the meaning of () 

} catch (error) {}
console.log({'a':a})

why this script work, what is the meaning of () in try-catch .

the { a } = b is wrong but ({ a } = b) is correct and the variable will go out of try-catch and give new value to a.

if there are a function in () may be a IIFE, if in expressions the () is a Grouping operator.and in my example,what is the meaning of ()