Extjs中的迭代要领

EXTJS 有许多的迭代要领，譬喻,你大概已知道的Ext.each，但尚有其它一些不为人知且很有效的要领。起首，扼要回首下Ext.each:

为每一个数组的成员应用统一个要领，它根基上是一个更利便的轮回情势

var people = ['Bill', 'Saul', 'Gaius'];

//using each to detect Cylons:
Ext.each(people, function (person, index)
{
    var cylon = (index + 1) % 2 == 0; //every second man is a toaster
    alert(person + (cylon ? ' is ' : ' is not ') + 'a fraking cylon');
});

//is the same as
for (var i = 0; i < people.length; i++)
{
    var person = people[i];
    var cylon = (index + 1) % 2 == 0; //every second man is a toaster

    alert(person + (cylon ? ' is ' : ' is not ') + 'a frakin cylon');
};

var ships = { 'Bill': 'Galactica', 'Laura': 'Colonial One' };

Ext.iterate(ships, function (key, value)
{
    alert(key + "'s ship is the " + value);
});

//is the same as
for (key in ships)
{
    var value = ships[key];
    alert(key + "'s ship is the " + value);
}

用Ext.iterate在数组上，与Ext.each完全沟通。
each和iterate要领都有第三个可选参数scope。
另一个有效的能力是你可以更利便的重用沟通的要领:

var myFunction = function (item, index)
{
    //does some clever thing
}

Ext.each(people, myFunction);
Ext.each(['another', 'array'], myFunction);

var animals = [
  { name: 'Ed', species: 'Unknown' },
  { name: 'Bumble', species: 'Cat' },
  { name: 'Triumph', species: 'Insult Dog' }
];

Ext.pluck(animals, 'species'); //returns ['Unknown', 'Cat', 'Insult Dog']
Ext.pluck(animals, 'name'); //returns ['Ed', 'Bumble', 'Triumph']

此要领自4.0.0不提议行使，请用Ext.Array.pluck取代.

(4.0.0之后过期)数组中全部成员挪用统一个要领，并返回功效，行使用上例animals：

var describeAnimal = function (animal)
{
    return String.format("{0} is a {1}", animal.name, animal.species);
}

var describedAnimals = Ext.invoke(animals, describeAnimal);
console.log(describedAnimals); // ['Ed is a Unknown', 'Bumble is a Cat', 'Triumph is a Insult Dog'];

Ext.invoke与Ruby的荟萃要领相同，使得更轻易转换数组，任何增进的参数都可通过Ext.invoke转达。
此要领自4.0.0不提议行使，4.X系列版本后将被移除。

Ext.Partition将数组拆分成两部门。

var trees = [
  { name: 'Oak', height: 20 },
  { name: 'Willow', height: 10 },
  { name: 'Cactus', height: 5 }
];

var isTall = function (tree) { return tree.height > 15 };

Ext.partition(trees, isTall);

//returns:
[
  [{ name: 'Oak', height: 20}],
  [{ name: 'Willow', height: 10 }, { name: 'Cactus', height: 5}]
]

此要领自4.0.0不提议行使，4.X系列版本后将被移除。

var numbers = [1, 2, 3, 4, 5];
Ext.min(numbers); //1
Ext.max(numbers); //5
Ext.sum(numbers); //15
Ext.mean(numbers); //3

原文地点：Ext JS iterator functions

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