Question

说我在javascripts中有这样的东西：

var obj = {
  subObj : {}
};
var type = 'subObj';

如何获得obj's subObj w / type？例如，我想做类似的事情：

obj.(type);

Answer 1

obj[type]

您使用下标符号。

11.2.1 Property Accessors

使用点表示法按名称访问属性：

MemberExpression . IdentifierName
CallExpression . IdentifierName

或括号表示法：

MemberExpression [ Expression ]
CallExpression [ Expression ]

Answer 2

您可以在JavaScript中处理关联数组之类的对象，因此您将能够访问内部对象，如：

var obj = {
    subObj : {}
};

var type = "subObj";
var subObj = obj[type];

Answer 3

如果有人想知道如何（动态地）访问子属性，我找到了一种方法，如果有更简单的方法，请告诉我：

function getPropertyByKeyPath(targetObj, keyPath) { 
  var keys = keyPath.split('.');
  if(keys.length == 0) return undefined; 
  keys = keys.reverse();
  var subObject = targetObj;
  while(keys.length) {
   var k = keys.pop();
   if(!subObject.hasOwnProperty(k)) {
    return undefined;
   } else {
    subObject = subObject[k];
   }
 }
 return subObject;
}

例如：

      var o = {result : {info:{ version:1, comment: 'test'}}};
      var subObject = getPropertyByKeyPath(o, 'result.info');
      console.log(subObject);

会导致：

{version: 1, comment: "test"}

Answer 4

obj[type]

根本没有任何意义 - 你没有访问TYPES，这些是简单的属性 - 可以通过obj[keyName]或类似的东西访问它们但是使用type是非常混乱的，并且是缺乏理解

Answer 5

    var obj = {
      subObj : {}
    }
    var type = 'subObj';

    console.log(typeof obj.subObj); //will print "object"
    console.log(obj.subObj); //will print "{}"

    //You can add a new propery like this:
    obj.subObj.newProperty = 'hello';
    console.log(typeof obj.subObj.newProperty); //will print "string"
    console.log(obj.subObj.newProperty); //will print "hello"

    // you can also add new properties like this
    obj.subObj['newProperty'] = 5; // this is very useful if you have to add properties with names that use reserved words or that contain illegal characters.
    console.log(typeof obj.subObj.newProperty); //will print "number"
    console.log(obj.subObj.newProperty); //will print "5"

    //In the case where you're using reserved or illegal words you'l have to do this  
    obj.subObj['new/Property'] = 'cat'; // this is very useful if you have to add properties with names that use reserved words or that contain illegal characters.
    console.log(typeof obj.subObj['new/Property']); //will print "number"
    console.log(obj.subObj['new/Property]); //will print "5"

    // and add another property in  the chain:
    obj.subObj['new/PropertyGroup']={
'illegal/name':'value', 
acceptableName: 5, 
andotherObject:{},
'illegally&Named(object)':{} 
}

通过变量中的键名获取javascript对象属性

5 个答案:

11.2.1 Property Accessors