Question

I have two or more javascript objects. I want to merge them adding values of common properties and then sort them in descending order of values.

e.g.

var a = {en : 5,fr: 3,in: 9}
var b = {en: 8,fr: 21,br: 8}

var c = merge(a,b)

c should then be like this:

c = {
fr: 24,
en: 13,
in:9,
br:8
} 

i.e. both objects are merge, values of common keys are added and then keys are sorted.

Here’s what I’ve tried:

var a = {en : 5,fr: 3,in: 9}
var b = {en: 8,fr: 21,br: 8}
c = {}

// copy common values and all values of a to c
for(var k in a){
  if(typeof b[k] != 'undefined'){  
    c[k] = a[k] + b[k]  
  }
  else{ c[k] = a[k]}
}

// copy remaining values of b (which were not common)
for(var k in b){
 if(typeof c[k]== 'undefined'){
  c[k] = b[k]
 }
} 

// Create a object array for sorting
var arr = [];

for(var k in c){
 arr.push({lang:k,count:c[k]})
}

// Sort object array
arr.sort(function(a, b) {
   return b.count - a.count;
})

but I dont think its good. So many loops 🙁 It would be nice if someone can provide a less messy and good code.

Answer 1

It is not possible to sort the properties of an object, you can however sort an array:

var merged = $.extend({}, a);
for (var prop in b) {
    if (merged[prop]) merged[prop] += b[prop];
    else merged[prop] = b[prop];
}
// Returning merged at this point will give you a merged object with properties summed, but not ordered.
var properties = [];
for (var prop in merged) {
    properties.push({
        name: prop,
        value: merged[prop]
    });
}
return properties.sort(function(nvp1, nvp2) {
    return nvp1.value - nvp2.value;
});