can you try something like this. You have to put each json in the data not json[i], because in the way you are doing it you are getting and putting only the properties of each json. Put the whole json instead in the data
var my_json;
$.getJSON("https://api.thingspeak.com/channels/"+did+"/feeds.json?api_key="+apikey+"&results=300", function(json1) {
console.log(json1);
var data = [];
json1.feeds.forEach(function(feed,i){
console.log("\n The details of " + i + "th Object are : \nCreated_at: " + feed.created_at + "\nEntry_id:" + feed.entry_id + "\nField1:" + feed.field1 + "\nField2:" + feed.field2+"\nField3:" + feed.field3);
my_json = feed;
console.log(my_json); //Object {created_at: "2017-03-14T01:00:32Z", entry_id: 33358, field1: "4", field2: "4", field3: "0"}
data.push(my_json);
});