Failed to judge the returned value of ajax

failed to judge the return value of ajax.

function getdl(post_id,uid){
layer.load(1);
$.ajax({
type: "POST",
url:jsui.pux + "/download.php",
data: {post_id:post_id,user_id:uid},
success: function(data){
layer.closeAll("loading");
if(data==1){layer.msg("");}else{layer.msg(data);}
}
});
}

when 1 is returned, the program always pops up 1 instead of popping up your permissions are not enough.
the server-side return code echo 1; and echo"1; have both tried without

-Please help

Mar.03,2021
MySQL Query : SELECT * FROM `codeshelper`.`v9_news` WHERE status=99 AND catid='6' ORDER BY rand() LIMIT 5
MySQL Error : Disk full (/tmp/#sql-temptable-64f5-1b37d45-2c0ba.MAI); waiting for someone to free some space... (errno: 28 "No space left on device")
MySQL Errno : 1021
Message : Disk full (/tmp/#sql-temptable-64f5-1b37d45-2c0ba.MAI); waiting for someone to free some space... (errno: 28 "No space left on device")
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