var selection = '$test[0] = 1;'
var matches = selection.match(/(\d)/g);
//var matches = selection.match(/[\[|'"](\d)[\]|'|"]/g);
for (i in matches) {
	number = parseInt(matches[i]);
	selection = selection.replace(matches[i], (number+1));
	trace(matches[i]);
}
//ergebnis: $test[2] = 1;