Pressing ENTER : Gets "Auto" characters ?

The expression inside single quotes is interpreted as a single string. When you press ENTER, it automatically adds string concatenation symbols to keep it as one continuous string.

In your example, the behavior is controlled by the Insert string concatenation on Enter setting. 

You can use $$ ... $$ quoting (see Double-quoted identifiers) instead of ‘...’ to avoid string concatenation when inserting a new line:

AS
$$
  var v_isfubar = 0;
$$
;

Alternatively, you can disable the Insert string concatenation on Enter setting if you don't need it.

Thanks I have to disable the setting