Promise sample

sum3.js

//sum([1,2,3]) == 6

function sum3() {
  var a = sum([1]);
  var b = sum([1,2]);
  var c = sum([1,2,3]);
  return a + b + c;
}

function sum(nums) {
  var cum = 0;
  for (var i = 0; i < nums.length; i++) {
    cum += nums[i];
  }
  return cum;
}

sum3_promise.js

/* sum([1,2,3]).then(function(res) {
 *   // res == 6
 * });
 */ 
function sum(nums) {
  var promise = new Parse.Promise();
  setTimeout(500, function() {
    var cum = 0;
    for (var i = 0; i < nums.length; i++) {
      cum += nums[i];
    }
    promise.resolve(cum);
  });
  return promise;
}

/* sum3().then(function(res) {
 *   // res == 6
 * });
 */ 
function sum3() {
  return sum([1]).then(function(a) {
    return Parse.Promise.as(a, [1,2]);
  }).then(function(a, hoge) {
    return sum(hoge).then(function(b) {
    return Parse.Promise.as(a, b, [1,2,3]);
    });
  }).then(function(a, b, hoge) {
    return sum(hoge).then(function(c) {
      return Parse.Promise.as(a+b+c);
    });
  });
}

function sum3_2() {
  var promises = [ sum([1]), sum([1,2]), sum([1,2,3]) ];
  return Parse.Promise.when(promises, function(a,b,c) {
    return Parse.Promise.as(a+b+c);
  });
}

function sum3_3() {
  var a_, b_;
  return sum([1]).then(function(a) {
    a_ = a;
    return sum([1,2]);
  }).then(function(b) {
    b_ = b;
    //a_ = 'hogehoge';
    return sum([1,2,3]);
  }).then(function(c) {
    return Parse.Promise.as(a_+b_+c);
  });
}

function sum3_4() {
  return sum([1]).then(function(a) {
    return sum([1,2]).then(function(b) {
      return sum([1,2,3]).then(function(c) {
        return Parse.Promise.as(a+b+c);
      });
    });
  });
}