var jsText='function(a){alert(a)}';
var jscode=new Function('return '+jsText)();
jscode(2);
2.处理该类型字符串
var str=’{"code":"TX_STEP-10","optTime":"2015-05-19 15:44:24","value":"消息存储"},{"code":"TX_STEP-20","optTime":null,"value":"到达预定队列"}‘
var jsonArr=eval('['+str+']');
$.each(jsonArr,function(i,v){
alert(v.code)
});