基于子对象的特定键值以排序顺序迭代 JavaScript 对象

Interesting question... One plain JavaScript solution is to create an index for your objects in a separate array, based on the 'Surname' property. Something like this¹:

var peopleobj = { 
   "0291" : { "Forename" : "Jeremy", "Surname" : "Dyson" },
   "0398" : { "Forename" : "Billy", "Surname" : "Bunter" },
   "6714" : { "Forename" : "Harry", "Surname" : "Peterson" },
   "9080" : { "Forename" : "Barry", "Surname" : "Mainwaring" }
};

var index = [];

// build the index
for (var x in peopleobj) {
   index.push({ 'key': x, 'Surname': peopleobj[x]['Surname'] });
}

// sort the index
index.sort(function (a, b) { 
   var as = a['Surname'], 
       bs = b['Surname']; 

   return as == bs ? 0 : (as > bs ? 1 : -1); 
}); 

现在你可以遍历你的 index 数组了:

Now you would be able to iterate over your index array:

for (var i = 0; i < index.length; i++) {
   console.log(peopleobj[index[i]['key']]['Surname']);
}

结果(在 Firebug 控制台中测试):

Result (Tested in Firebug console):

Bunter
Dyson
Mainwaring
Peterson

你可能想把它包装成某种可重用的 Iterator 对象，即使它很难像 Perl 一样简洁:

You may want to wrap this up into some sort of reusable Iterator object, even though it would be difficult to get as terse as Perl:

// Our reusable Iterator class:
function MyIterator (o, key) {
   this.index = [];
   this.i = 0;
   this.o = o;

   for (var x in o) {
      this.index.push({ 'key': x, 'order': o[x][key] });
   }

   this.index.sort(function (a, b) { 
      var as = a['order'], 
          bs = b['order']; 

      return as == bs ? 0 : (as > bs ? 1 : -1); 
   }); 

   this.len = this.index.length;
}

MyIterator.prototype.next = function () {
   return this.i < this.len ?
          this.o[this.index[this.i++]['key']] :
          null;
};

然后按如下方式使用:

// Our JavaScript object:
var peopleobj = { 
   "0291" : { "Forename" : "Jeremy", "Surname" : "Dyson" },
   "0398" : { "Forename" : "Billy", "Surname" : "Bunter" },
   "6714" : { "Forename" : "Harry", "Surname" : "Peterson" },
   "9080" : { "Forename" : "Barry", "Surname" : "Mainwaring" }
};

// Build the Iterator object, using the 'Surname' field:
var surnameIter = new MyIterator(peopleobj, 'Surname');

// Iterate:
var i;

while (i = surnameIter.next()) {
   console.log(i['Surname'] + ' ' + i['Forename']);
}

结果:

Bunter Billy
Dyson Jeremy
Mainwaring Barry
Peterson Harry

<小时>

¹ 您可能想要使用 hasOwnProperty() 方法来确保属性属于你的对象而不是继承自 Object.prototype:

for (var x in peopleobj) {
   if (peopleobj.hasOwnProperty(x)) {
      index.push({ 'key': x, 'Surname': peopleobj[x]['Surname'] });
   }
}

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