meriyah: Bare block statement

There is a troublesome change in latest various js implementations. When a statement starts with {, it used to be a block statement.

I am pretty sure that’s the case in early 2016. Back then, when you write bare {a:1}, it’s not an object literal, Chrome (and every other js implementations) thinks is a block statement with one inner statement 1 and it’s labelled with a, similar with

{
  loop: while(false) {
  }
}

Firefox still keeps this old behavior, but nodejs/chome (v8), safari are changed.

	{a: 1}	{a:1,b:2}	{a:while(false){}}
chrome/nodejs	object literal	object literal	block statement
firefox	block statement	syntax error	block statement
safari	object literal	object literal	syntax error

I am not clear about ECMA spec, it seems following the old behaviour (firefox)?? Many parsers are still using the old behaviour including babel parser. But v8 and safari have moved to a more intuitive behaviour. What should we do here?

Related to #136

About this issue

Original URL
State: closed
Created 4 years ago
Comments: 15 (15 by maintainers)

Most upvoted comments

Bingo! This is a false alarm.

As you checked webkit and v8 source code, it’s indeed parsed as statement. I can confirm this with nodejs (not the interactive console).

⋊> ~/playground cat > t.js
{a:1,b:2}
⋊> ~/playground node t.js
/Users/huocp/playground/t.js:1
{a:1,b:2}
      ^

SyntaxError: Unexpected token ':'

So it’s just some special parsing in nodejs/chrome/safari interactive console. I totally understand why they do this in interactive console.

The real js parsers were not changed.

3cp on Oct 31, 2020

I am not going to try this hard topic anytime soon 😃

3cp on Oct 28, 2020