Group json data by a given object

Question

I have a list:

var dataString='[ 
 { "category" : "Search Engines", "hits" : 5, "bytes" : 50189 },
 { "category" : "Content Server", "hits" : 1, "bytes" : 17308 },
 { "category" : "Content Server", "hits" : 1, "bytes" : 47412 },
 { "category" : "Search Engines", "hits" : 1, "bytes" : 7601 },
 { "category" : "Business", "hits" : 1, "bytes" : 2847 },
 { "category" : "Content Server", "hits" : 1, "bytes" : 24210 },
 { "category" : "Internet Services", "hits" : 1, "bytes" : 3690 },
 { "category" : "Search Engines", "hits" : 6, "bytes" : 613036 },
 { "category" : "Search Engines", "hits" : 1, "bytes" : 2858 } 
]';

where category is a variant pattern that I care, I wanted to group these, the rest is non-standard variant that I do not care.

Group type an array of Business in which I can go through all the business if I want and so on..

Answer 1

I created an example that groups the array elements, by the property category of each item, creating an object in which each key is a group containing the corresponding elements:

var dataString= '['+
 '{ "category" : "Search Engines", "hits" : 5, "bytes" : 50189 },'+
 '{ "category" : "Content Server", "hits" : 1, "bytes" : 17308 },'+
 '{ "category" : "Content Server", "hits" : 1, "bytes" : 47412 },'+
 '{ "category" : "Search Engines", "hits" : 1, "bytes" : 7601 },'+
 '{ "category" : "Business", "hits" : 1, "bytes" : 2847 },'+
 '{ "category" : "Content Server", "hits" : 1, "bytes" : 24210 },'+
 '{ "category" : "Internet Services", "hits" : 1, "bytes" : 3690 },'+
 '{ "category" : "Search Engines", "hits" : 6, "bytes" : 613036 },'+
 '{ "category" : "Search Engines", "hits" : 1, "bytes" : 2858 } '+
']';

var data = JSON.parse(dataString);

var groupedData = {};

for (var it = 0; it < data.length; it++) {
  var item = data[it];
  if (!groupedData[item.category])
    groupedData[item.category] = [];
  groupedData[item.category].push(item);
}

document.body.innerHTML = "";
document.body.appendChild(document.createTextNode(JSON.stringify(groupedData, null, 4)));

body { white-space: pre; font-family: monospace; }

Answer 2

It is a solution that brings a final result identical to that of reply @Miguelangelo, only that using a library that I really like and use some time (which apparently is abandoned by the developer) the jLinq.js.

Implementation would thus be:

var dataString= '['+
 '{ "category" : "Search Engines", "hits" : 5, "bytes" : 50189 },'+
 '{ "category" : "Content Server", "hits" : 1, "bytes" : 17308 },'+
 '{ "category" : "Content Server", "hits" : 1, "bytes" : 47412 },'+
 '{ "category" : "Search Engines", "hits" : 1, "bytes" : 7601 },'+
 '{ "category" : "Business", "hits" : 1, "bytes" : 2847 },'+
 '{ "category" : "Content Server", "hits" : 1, "bytes" : 24210 },'+
 '{ "category" : "Internet Services", "hits" : 1, "bytes" : 3690 },'+
 '{ "category" : "Search Engines", "hits" : 6, "bytes" : 613036 },'+
 '{ "category" : "Search Engines", "hits" : 1, "bytes" : 2858 } '+
']';

var data = JSON.parse(dataString);

var result = jlinq.from(data)
                  // para ser case sensitive
                  .useCase()
                  // aplica group pelo campo categoria
                  .group("category");

// para imprimir do DOM (copiado na cara dura da implementação do @MiguelAngelo)
document.body.innerHTML = "";
document.body.appendChild(document.createTextNode(JSON.stringify(result, null, 4)));

body { white-space: pre; font-family: monospace; }

<script src="http://hugoware.net/resources/projects/jlinq/jlinq.min.demo-version.js"></script>

Example also available here in jsFiddle.

Advantages of the library

You have many more features available besides the group, as we can see here in the demo and in the library test file.