JavaScript 对象声明语法 - 变量名作为属性
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JavaScript object declaration syntax - variable names as properties
提问by tommcdo
JavaScript gives you a lot of ways to declare objects. When you have most of the data available at hand, the most convenient (in my opinion) is as follows:
JavaScript 为您提供了多种声明对象的方法。当您手头有大部分可用数据时，最方便的（在我看来）如下：
var person = {
name: 'John',
age: 23
}; // "object literal syntax"
A curious thing about this syntax is that it is identical to this:
这种语法的一个奇怪之处在于它与此相同：
var person = {
'name': 'John',
'age': 23
}; // "object literal syntax"
That is, you can use quotes or omit them for the property names.
也就是说，您可以对属性名称使用引号或省略它们。
When comparing that to the way setting a single property works, you have two options:
将其与设置单个属性的工作方式进行比较时，您有两个选择：
person.birthday = "January 12"; // "dot syntax"
or
或者
person['birthday'] = "January 12"; // "array syntax"
The "dot syntax" only works when the right operand is the actual property name. If you want to use a variable for the property name, you have to use "array syntax", i.e.:
“点语法”仅在正确的操作数是实际属性名称时才有效。如果要为属性名称使用变量，则必须使用“数组语法”，即：
var prop = "birthday";
person[prop] = "January 12";
Now, is it possible to use a variable for the property name in the "object literal syntax"? Since it doesn't matter if you quote the property names, there doesn't seem to be an obvious way to use a variable there. I'm looking for something like this:
现在，是否可以在“对象文字语法”中为属性名称使用变量？由于引用属性名称无关紧要，因此似乎没有明显的方法可以在那里使用变量。我正在寻找这样的东西：
var prop = "birthday";
var person = {
name: 'John',
age: 23,
(prop): 'January 12'
};
Here I'm using (prop) as the imaginary syntax used to express that this is a variable and not a literal string.
在这里，我使用 (prop) 作为虚构的语法，用于表示这是一个变量而不是文字字符串。
Thanks.
谢谢。
采纳答案by dwhieb
ES6 now allows for this:
ES6 现在允许这样做：
var obj = {
[prop]: 'value'
};
回答by geekman
No, this will not work, that is why, if you are dynamically setting property names, array like notation is suggested and used.
不，这行不通，这就是为什么，如果您动态设置属性名称，建议并使用类似符号的数组。
var k='propertyname';
object[k]="value";
this works while using the dot notation to set index or property name from vatiable is not possible.
这在使用点符号从 vatiable 设置索引或属性名称是不可能的时有效。
回答by Zack Morris
For people who need a drop-in replacement for dot syntax where the keys are objects instead of strings (say for nesting inside a parent Object), here are some workarounds:
对于需要直接替换点语法的人，其中键是对象而不是字符串（比如嵌套在父对象中），这里有一些解决方法：
var developers = {
person: {
'name': 'John',
'age': 23
},
anarchist: (function(){ var a = {};
a['name'] = 'John';
a['age'] = 23;
a[false] = false;
a[1] = 1;
a[window] = window;
return a; })(),
conformist: _.object([
['name', 'John'],
['age', 23],
[false, false],
[1, 1],
[window, window]
])
};
// console.log(developers); // <- to see var dump in Firebug
The anarchist element uses a self-executing-functionthat gets garbage collected after the call, and the conformist element uses the _.object()function if you can include underscore.js in your site.
anarchist 元素使用自执行函数在调用后收集垃圾，如果您可以在站点中包含 underscore.js，conformist 元素使用_.object()函数。
I wish that the built-in Object() and Array() functions allowed for passing in keys and values the way underscore.js does it :-)
我希望内置的 Object() 和 Array() 函数允许以 underscore.js 的方式传递键和值:-)
回答by sra
You can not do this with objects, but if you consider using a constructor function instead, it could look something like this:
你不能使用对象做到这一点，但如果你考虑使用一个构造函数，而不是，它可能是这个样子：
var prop = "birthday";
var Person = function() {
this.name = "Bob";
this[prop] = "January 12";
};
var bob = new Person();
Of course you still have the array notation here, but maybe you like this aproach anyway :)
当然，这里仍然有数组表示法，但也许您仍然喜欢这种方法:)
