Execution rules for try, catch, and finally in js

try: The statement tests the error of the code block. Generally, the code that may go wrong is placed here.

catch: Only when an error occurs in the code block in try, the code here will be executed. The parameter err is recorded. With the error message of the code in try

finally: The code inside will be executed regardless of whether there is an exception

try{
 console.log(0);
 }catch (err){
 console.log(1);
 console.log(hello);
 }finally {
 console.log(2);
 }
 //最后结果分别打印出 0 2
 /*
 try{
 a.b.c();
 }catch (e){
 console.log(1);
 console.log(hello);
 }finally {
 console.log(2);
 }
 */
 //最后结果分别打印出 1 2 报错:hello is not defined
 /*
 try{
 a.b.c();
 }catch (e){
 console.log(1);
 try{
  console.log(hello);
 }catch (e){
  console.log(3);
 }
 }finally {
 console.log(2);
 console.log(word);
 } 
 */
 //最后结果分别打印出 1 3 2 报错:word is not defined
 /*
 try{
 a.b.c();
 }catch (e){
 console.log(1);
 console.log(hello);
 }finally {
 console.log(2);
 console.log(word);
 }*/
 //最后结果分别打印出 1 2 报错:word is not defined

Summary:

When the code inside try reports an error, the code inside catch will be executed. The code in finally will always be executed.

In catch and finally, normal code will be executed sequentially from top to bottom.

If only the code in catch is wrong, the code in catch will be reported. Error

If both catch and finally are wrong, the error in finally will be reported

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