@Kingwl this is a good change, but upon further review it seems like its not comprehensive. There are a number of other places where we are still adding hoisted declarations at the end of the scope rather than at the beginning.

If you search for all references to endLexicalEnvironment you'll see a number of additional cases in:

• src/compiler/transformers/es2015.ts
• src/compiler/transformers/es2017.ts
• src/compiler/transformers/esnext.ts
• src/compiler/transformers/generators.ts
• src/compiler/transformers/module.ts
• src/compiler/transformers/system.ts
• src/compiler/transformers/ts.ts

Most (but not all) of these cases look something like this:

addRange(statements, endLexicalEnvironment());

To fully resolve these (and consider the linked issue closed), I would recommend adding the following function to src/compiler/core.ts (after the existing addRange function):

export function prependRange<T>(to: T[], from: ReadonlyArray<T> | undefined) {
    if (some(from)) to.unshift(...from);
}

Then I would replace these specific addRange calls with prependRange.