It seems there is an issue with High

========
var
  fruits : array of String = ('Banana', 'Orange', 'Apple', 'Mango',
'Banana', 'Abacate', 'Apple');
begin
  TJSArray(fruits).push('kiwi');
  for Index := Low(fruits) to High(fruits) do
     console.log( fruits[Index] );
end;
========
JS output
//-------------
$mod.fruits.push("kiwi");
for ($mod.Index = 0; $mod.Index <= 6; $mod.Index++)
window.console.log($mod.fruits[$mod.Index]);

console output:
------------------
Banana
Orange
Apple
Mango
Banana
Abacate
Apple

//---the correct should be-------------------------
$mod.fruits.push("kiwi");
for ($mod.Index = 0; $mod.Index < $mod.fruits.length; $mod.Index++)
window.console.log($mod.fruits[$mod.Index]);

Banana
Orange
Apple
Mango
Banana
Abacate
Apple
kiwi

ahn, if we change High to Length, it works as expected.

  TJSArray(fruits).push('kiwi');
  for Index := Low(fruits) to Length(fruits) do
     console.log( fruits[Index] );
it translates corretly
$mod.fruits.push("kiwi");
    for ($mod.Index = 0; $mod.Index <= 7; $mod.Index++)
window.console.log($mod.fruits[$mod.Index]);

---------
Banana
Orange
Apple
Mango
Banana
Abacate
Apple
kiwi

Fixed.

Mattias