Question

In javascript, here is my start array:

[{
   name: 'aaa',
   value: 1
 },
 {
   name: 'bbb',
   value: 0
 },
 {
   name: 'bbb',
   value: 1
}]

I want to transform it into this array as result:

[{
   name: 'aaa',
   value: 1
 },
 {
   name: 'bbb',
   value: [0, 1]
 }]

I need a good and simple algorithm to do this

Answer 1

How about:

var array = [{
   name: 'aaa',
   value: 1
 },
 {
   name: 'bbb',
   value: 0
 },
 {
   name: 'bbb',
   value: 1
}];

var map = {};    
for(var i = 0; i < array.length; i++) {
  var name = array[i].name;
  if (map[name] === undefined) {
    map[name] = [];
  }
  map[name].push(array[i].value);
}

var result = [];
for(var key in map) {
  var value = map[key];
  result.push({
    name: key, 
    value: value.length === 1 ? value[0] : value
  });
}

Easiest way is to create a map to keep track of which names are used. Then convert this map back to an array of objects.

If you want to use Arrays for value then change it to:

result.push({
  name: key, 
  value: value
});