JSONAppendExpr ::= "append" "json" ExprSingle "into" ExprSingle

(for explanatory purposes, suboperands are replaced with a variable containing the result of their evaluation)

append json $c into $a

$a must be an array. Otherwise, jerr:JNUP0008 is raised.

Creates the update primitive insert-into-array($a, $a()+1, $c)

              append json (1,2) into $a