OL3 how group feature?

Question

There are several feature how to grouped into categories depending on the feature?

id : "1" 
lat : 88.777 
lon : 88.777 
name : "Name company 1" 
cat_id: "12" 

id : "2" 
lat : 77.777 
lon : 77.777 
name : "Name company 2" 
cat_id: "30" 

id : "3" 
lat : 99.777 
lon : 99.777 
name : "Name company 3" 
cat_id: "12" 

cat_id = name category

There are several features how grouped by category? Depending on the category feature.

the logic of something like that:

if(value['Category'] == '12'){ 
 //put feature in a group of 12
} 
else if(value['Category'] == '30'){ 
 //put feature in a group of 30
}

Answer 1

Example of iterating through vector layer's features:

var groups = {};

layer.getSource().forEachFeature(function (feature) {
    var cat_id = feature.getProperties().cat_id;
    groups[cat_id] = groups[cat_id] || [];
    groups[cat_id].push(feature);
});