How to create nested object dynamically?

Question

I need to create an object in this format by using JavaScript.

var results = {
 "A-1": [
 { "object": "daily", "type": "when", "field": "Period" }
 ],
 "A-2": [
 { "object": "weekly", "type": "when", "field": "Period" }
 ],
 "A-3": [
 { "object": "monthly", "type": "when", "field": "Period" }
 ],
 "B-1": [
 { "object": "Boston", "type": "who", "field": "City" },
 { "object": "AG", "type": "what", "field": "region" },
 { "object": "L1", "type": "where", "field": "Level" }
 ],
 "B-2": [
 { "object": "New York", "type": "who", "field": "City" },
 { "object": "AG", "type": "what", "field": "region" },
 { "object": "L2", "type": "where", "field": "Level" }
 ],
 "B-3": [
 { "object": "Paris", "type": "who", "field": "City" },
 { "object": "EURO", "type": "what", "field": "region" },
 { "object": "L1", "type": "where", "field": "Level" }
 ],
 "B-4": [
 { "object": "Boston", "type": "who", "field": "City" },
 { "object": "AG", "type": "what", "field": "region" },
 { "object": "L2", "type": "where", "field": "Level" }
 ]
};
var periodList = "daily,weekly,monthly";

The B- section key values are returned from web services in JSON format as shown below:

 [
 { "object": "Boston", "level": "L1", "region": "AG" },
 { "object": "Paris", "level": "L1", "region": "EURO" },
 { "object": "Boston", "level": "L2", "region": "AG" },
 { "object": "China", "level": "L1", "region": "AP" },
 { "object": "New York", "level": "L2", "region": "AG" }
]

Each B- object contains the city, region and level arrays.

Please help how to create this structure dynamically?

• Mark A. Fitzgerald: Should China be in your desired JSON output? Also, is key ojbect in the web service returned JSON a typo in your question?
• Monica: Sorry, it is typo in my returned data while I create this sample data.
• Monica: China is just another sample data. If added, another B-5 list should be created. Thank you for your help.
• Mark A. Fitzgerald: Thanks for the the clarifications. Are the A- key-array pairs constant?
• Monica: The A- key-values pairs are constant for "type" and "field". The "object" values are from a constant string of "daily,weekly,monthly".

Answer 1

Just use two simple loops:

var results = {};
var periods = periodList.split(",");
for (var i=0; i<periods.length; i++)
 results["A-"+(i+1)] = [
 {"object": periods[i], "type": "when", "field": "Period"}
 ];
for (var i=0; i<json.length; i++)
 results["B-"+(i+1)] = [
 {"object": json[i].object, "type": "who", "field": "City"},
 {"object": json[i].region, "type": "what", "field": "region"},
 {"object": json[i].level, "type": "where", "field": "Level"}
 ];

There is no arbitrary nesting, so you don't need recursion or anything heavy.

• Daniel Kucal: periods.lenght one more typo
• Monica: Thank you for your quick solution. I am much appreciated.
• Monica: Hi, What if I need to add the section A to each of B section instead? How can I show my new format?