I'd do it more or less like:
set(#input, "132,test1\n", "Global")
set(#input, "{#input}8931,test2\n", "Global")
set(#input, "{#input}1322221,test3\n", "Global")
set(#input, "{#input}5499,test4\n", "Global")
set(#sorted, $eval("
var outs = Array();
outs.length = 999999999;
var source =\"{#input}\";
var list = source.split(\"\\n\");
for (i in list) \{
parts = list[i].split(\",\");
outs[parts[0]] = list[i];
\}
var sortedlist = \"\";
for (j in outs) \{if (outs[j]) sortedlist = sortedlist +outs[j] +\"\\n\";\}
sortedlist;
"), "Global")
alert(#sorted)
Of course the set for #input would be in y