Firefox/Chrome: {} + {} etc.

Luke Hoban lukeh at microsoft.com
Fri Jan 27 08:38:07 PST 2012


JS REPLs tend to parse input as Program productions.  Parsing "{} + {}" as a block followed by a unary expression is correct according to ES5 grammar for Program.  IE behaves the same.  

Luke

From: es-discuss-bounces at mozilla.org [mailto:es-discuss-bounces at mozilla.org] On Behalf Of Axel Rauschmayer
Sent: Friday, January 27, 2012 8:21 AM
To: es-discuss
Subject: Re: Firefox/Chrome: {} + {} etc.

Ah! Good call. And, as expected, wrapping the first operand in parens makes the problem go away.

REPL input is tricky to parse correctly in JS, kind of between statements and expressions.


On Jan 27, 2012, at 16:56 , Bradley Meck wrote:


Chrome and FF are treating the leading {} as an empty block statement.

<snip>




More information about the es-discuss mailing list