JSFiddle - React, Tailwind, and code Playground

HTML

<link rel="stylesheet" href="http://ajax.googleapis.com/ajax/libs/jqueryui/1.8.4/themes/ui-lightness/jquery-ui.css">

JavaScript

$input = [ { animal: 'cat', name: 'Rocky', value: 1 },
           { animal: 'cat', name: 'Spot',  value: 2 },
           { animal: 'dog', name: 'Spot',  value: 3 } ];

$output = {animal:{},name:{},value:{}};

$input.forEach(function(v,i) { 
    $output.animal[v.animal] = 1;
    $output.name[v.name] = 1;
    $output.value[v.value] = 1;
});

$output.animal = Object.keys($output.animal);
$output.name = Object.keys($output.name);
$output.value = Object.keys($output.value);


document.write('<pre>' +
               JSON.stringify($output, null, 4) + 
              '</pre>');