underscore mixin

getdefault.js

// as python setdefault: put defaultValue in object if object[key] is undefined
_.mixin({
  setdefault:function(object,key,defaultValue){
    var d ={};
    d[key]=defaultValue;
    return _(object).defaults(d)[key];
  }
});

indexes.js

// returns the list of indexes matching a filterFunction
_.mixin({
  indexes:function(list,filterFunction){
    return _(list).chain().map(function(i,k){
      return [k,i];
    }).filter(function(i){
      return filterFunction(i[1]);
    }).pluck(0).value();
  }
});