I made it that way:
if I have:
var jsonArg1 = new Object();
jsonArg1.name = 'calc this';
jsonArg1.value = 3.1415;
var jsonArg2 = new Object();
jsonArg2.name = 'calc this again';
jsonArg2.value = 2.73;
var pluginArrayArg = new Array();
pluginArrayArg.push(jsonArg1);
pluginArrayArg.push(jsonArg2);
to convert pluginArrayArg (which is pure javascript array) into JSON array:
var jsonArray = JSON.parse(JSON.stringify(pluginArrayArg))