After Json_encode, the JSON data becomes [{"A" "1"}], how to change to {"A" "1"}

After Json_encode, the JSON data becomes [{"A", "1"}], how to change to {"A", "1"}

function Get_js_array ($sql) {
$result = mysql_query ($sql);
$arr = Array ();
while ($row = Mysql_fetch_array ($result, Mysql_assoc)) {
$arr [] = $row;  
}
$js = Json_encode ($arr);
Mysql_free_result ($result);
Mysql_close ($conn);
return $JS;
}

Please rewrite it according to this. Thank you
------to solve the idea----------------------
$js = Json_encode (Array_pop ($arr));
------to solve the idea----------------------
$js = Trim (Json_encode ($arr), ' [] ');

Your demand is strange, it was an array, but not an array representation.

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