Unos ejercicios basados en el uso de los helpers que me gustaria subir a gist para tenerlos ahi como referencia para mi y para otros

ArrayHelpers.js

// Using Array Helpers Excercise - This uses Filter()
const numbers = [10, 20, 30];
function reject(){
    let lessThanFifteen = numbers.filter(function(number){
  return number < 15;
});
  return ` Number that is less than 15 is: ${lessThanFifteen}`;
}
reject(); 

// Another Helper Excercise - This uses Find()
const ladders = [{ id: 1,height: 20 },{ id: 2, height: 30 },{ id: 3, height: 25 }];
function findWhere(array, criteria) {
  let property = Object.keys(criteria)[0] ;
  var results = array.find(function(result){
    return result[property] === criteria[property] ;
});
   return `Item # ${results.id} is a ladder of ${results.height} feet of height.`;

}
findWhere(ladders, { height: 25 }); 

// Another one for helpers this one is with reducer()
const desks = [ { type: 'sitting' },{ type: 'standing' },{ type: 'sitting' },{ type: 'sitting' }, { type: 'standing' }];
let deskTypes = desks.reduce(function(total,desk) {
  desk.type === 'sitting' ? ++total.sitting : ++total.standing;
     return total
},{ sitting: 0, standing: 0 });
deskTypes;

// Another one for helpers this one is with reducer()
const numeros = [1, 1, 2, 3, 4, 4]
function ElementoUnico(array) {
  return array.reduce((arr, num) => {
      if(arr.indexOf(num) === -1) {
        arr.push(array.find((n) => n === num))          
      }
      return arr;
  }, [])
}
ElementoUnico(numeros);;