try catch finally

[teazean]

文档: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Guide/Control_flow_and_error_handling#The_finally_block

The finally block contains statements to execute after the try and catch blocks execute but before the statements following the try...catch statement.

总结就是：『finally中的代码』总会执行，无视 try/catch 里面的任何 throw error&return，『finally中的代码』执行时机是先于任何『next/outer的语句』。

[teazean]

throw error demo

try {
  try {
    throw new Error('oops');
  }
  finally {
    console.log('finally');
  }
}
catch (ex) {
  console.error('outer', ex.message);
}

// Output:
// "finally"
// "outer" "oops"

[teazean]

return demo

function f() {
  try {
    console.log(0);
    throw 'bogus';
  } catch(e) {
    console.log(1);
    return true; // this return statement is suspended
                 // until finally block has completed
    console.log(2); // not reachable
  } finally {
    console.log(3);
    return false; // overwrites the previous "return"
    console.log(4); // not reachable
  }
  // "return false" is executed now  
  console.log(5); // not reachable
}
f(); // console 0, 1, 3; returns false