Syntax

$async[name]
  ...
$endAsync

Parameters

Parameter	Description
name	Required, exactly one argument (otherwise Invalid argument count for $async: N.). Evaluated when the block starts, then trimmed. It must be unique in the execution: reusing it raises Async block "name" already exists.

Behavior

• Text of the block. What the body writes is never sent. It is only returned by $await[name].
• Unawaited blocks. A block nobody awaits is waited for before the response is sent: it is never lost and never runs after the interaction has expired. (In BDFD itself the script ends without waiting for it.)
• Shared state. Temporary variables, $setVar and the services are shared with the rest of the script. The stack of user functions, loops and calls is private to the block (copied when it starts): a block started inside a $for sees the value of its own iteration.
• $stop, $break, $continue only end the block, not the script.
• Errors. An error in a block only surfaces at $await[name] (where $try can catch it) or, if nobody awaited the block, when the script ends. A script that fails stops its running blocks at their next step.
• Limits.
  • 25 blocks per execution at most (Too many async blocks (25 at most).).
  • $async cannot be written inside the argument of another function; it is a top-level structure.
  • Steps of the blocks count in the script’s step limit, and the command’s time budget (15 minutes) bounds $await and the wait for the end of the blocks.
• Structure errors. Missing $endasync., Unexpected $endasync..

Examples

$async[stats]
  $httpGet[https://example.com/stats.json]
  $httpResult
$endAsync
$async[quote]
  $httpGet[https://example.com/quote.txt]
  $httpResult
$endAsync
Stats: $await[stats]
Quote: $await[quote]

The two requests run together; the response is written once both are done.