functions.coffee

A = (a) ->
  a
  .filter (b) -> b.type is 'email'
  .map (b) -> b.value

B = (a) ->
  b.value for b in a when b.type is 'email'

array = [
  type: 'email'
  value: '[email protected]'
,
  type: 'email'
  value: '[email protected]'
,
  type: 'phone'
  value: '1234567890'
,
  type: 'email'
  value: '[email protected]'
,
  type: 'email'
  value: '[email protected]'
]

console.log A array
console.log B array

functions.js

// reusable helpers
var prop = function(name) {
  return function(o) {
    return o[name];
  }
};
var by = function(prop, value) {
  return function(o) {
    return o[prop] === value;
  };  
};

// actual code
var A = function(a) {
  return a
  .filter(by('type', 'email'))
  .map(prop('value'));
};
 
var B = function(a) {
  var _ret = [];
  a.forEach(function(b){
    if(b['type']==='email') _ret.push(b.value);
  });
  return _ret;
};
 
 
var array = [{
  'type': 'email',
  value: '[email protected]'
 
}, {
  'type': 'email',
  value: '[email protected]'
 
}, {
  'type': 'phone',
  value: '1234567890'
 
}, {
  'type': 'email',
  value: '[email protected]'
 
}, {
  'type': 'email',
  value: '[email protected]'
 
}];
 
console.log(A(array));
console.log(B(array));