how can I access to a variable in try block in other try block?

Question

http://blog.grossman.io/how-to-write-async-await-without-try-catch-blocks-in-javascript/ In this link, there are some codes that access to a variable in try catch but when I try this in my server It doesn't work because It's out of scope. how can I do this?

try {
  const foo = "bar"
} catch (e) {
  console.log(e)
}

try {
  console.log(foo) -> is not defined
} catch (e) {
  console.log(e)
}

Answer 1

The author of that post clearly did a mistake there––it happens to all of us.

So, the const declarations are block-scoped, like the docs say:

Constants are block-scoped, much like variables defined using the let statement. The value of a constant cannot change through re-assignment, and it can't be redeclared.

That's why you cannot access it outside of the try-catch block.

To solve the problem:

• Either use var instead of const:

  try {
    // When declared via `var`, the variable will
    // be declared outside of the block
    var foo = "bar"
  } catch (e) {
    console.log(e)
  }
  
  try {
    console.log(foo)
  } catch (e) {
    console.log(e)
  }
  

• Or you can declare the variable outside of the try-catch, using let:

  // Maybe it's clearer to declare it with let and 
  // assign the value in the first try-catch
  let foo;
  try {
    foo = "bar"
  } catch (e) {
     console.log(e)
  }
  
  try {
    console.log(foo)
  } catch (e) {
    console.log(e)
  }