[foo]

Вариант без понтов:

isEmpty=function(arr){return arr.toString()===""}
replace=function(arr){
   var newarr=[]
   for(var i in arr){
        if(arr[i].keys&&arr[i].generator){
            while(!isEmpty(arr[i].keys)){
               newarr.push({key: arr[i].keys[0], generator: arr[i].generator})
               arr[i].keys=arr[i].keys.slice(1)
            }
        }
   }
   return newarr
}