JavaScript 枚举器？
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JavaScript enumerator?
提问by wong2
I want to define a list of constants that have continuous integer value, for example:
我想定义一个具有连续整数值的常量列表，例如：
var config.type = {"RED": 0, "BLUE" : 1, "YELLO" : 2};
But it's boring to add a "XX" : yevery time I need to add a new element in it.
So I'm wondering is there something like enumeratorin C so I can just write:var config.type = {"RED", "BLUE", "YELLO"}and they are given unique integer value automatically.
但是"XX" : y每次需要在其中添加新元素时都添加一个很无聊。
所以我想知道enumerator在 C 中有没有类似的东西，所以我可以写：var config.type = {"RED", "BLUE", "YELLO"}并且它们会自动获得唯一的整数值。
回答by Locksfree
You could also try to do something like this:
你也可以尝试做这样的事情：
function Enum(values){
for( var i = 0; i < values.length; ++i ){
this[values[i]] = i;
}
return this;
}
var config = {};
config.type = new Enum(["RED","GREEN","BLUE"]);
// check it: alert( config.type.RED );
or even using the arguments parameter, you can do away with the array altogether:
甚至使用 arguments 参数，您可以完全取消数组：
function Enum(){
for( var i = 0; i < arguments.length; ++i ){
this[arguments[i]] = i;
}
return this;
}
var config = {};
config.type = new Enum("RED","GREEN","BLUE");
// check it: alert( config.type.RED );
回答by Naftali aka Neal
Just use an array:
只需使用一个数组：
var config.type = ["RED", "BLUE", "YELLO"];
config.type[0]; //"RED"
回答by Marc B
Use an array ([]) instead of an object ({}), then flip the array to swap keys/values.
使用数组 ( []) 而不是对象 ( {})，然后翻转数组以交换键/值。
回答by user113716
I suppose you could make a function that accepts an Array:
我想你可以制作一个接受数组的函数：
function constants( arr ) {
for( var i = 0, len = arr.length, obj = {}; i < len; i++ ) {
obj[ arr[i] ] = i;
}
return obj;
}
var config.type = constants( ["RED", "BLUE", "YELLO"] );
console.log( config.type ); // {"RED": 0, "BLUE" : 1, "YELLO" : 2}
Or take the same function, and add it to Array.prototype.
或者把同样的函数，加入到Array.prototype中。
Array.prototype.constants = function() {
for( var i = 0, len = this.length, obj = {}; i < len; i++ ) {
obj[ this[i] ] = i;
}
return obj;
}
var config.type = ["RED", "BLUE", "YELLO"].constants();
console.log( config.type ); // {"RED": 0, "BLUE" : 1, "YELLO" : 2}
回答by Darlan Dieterich
Define the Enum:
定义枚举：
var type = {
RED: 1,
BLUE: 2,
YELLO: 3
};
get the color:
获取颜色：
var myColor = type.BLUE;
