Get random records form mongodb via map/reduce

finalize.js

function(k, v) {
  return v.a ? v.a.map(function(x) {
    return x.k
  }) : [v.k]
}

finalize.min.js

function(k,v){return v.a?v.a.map(function(x){return x.k}):[v.k]}

map.js

function() { 
  emit(0, {k: this, v: Math.random()}) 
}

map.min.js

function(){emit(0,{k:this,v:Math.random()})}

reduce.js

function(k, v) {
  var a = []
  v.forEach(function(x) {
    a = a.concat(x.a ? x.a : x)
  })
  return {a:a.sort(function(a, b) {
    return a.v - b.v;
  }).slice(0, 3 /*how many records you want*/)}; 
}

reduce.min.js

function(k,v){var a=[];v.forEach(function(x){a=a.concat(x.a?x.a:x)});return{a:a.sort(function(a,b){return a.v-b.v}).slice(0,3)}}