I want to define a list of constants that have continuous integer value, for example:
var config.type = {"RED": 0, "BLUE" : 1, "YELLO" : 2}; But it's boring to add a "XX" : y every time I need to add a new element in it.
So I'm wondering is there something like enumerator in C so I can just write:
var config.type = {"RED", "BLUE", "YELLO"} and they are given unique integer value automatically.
5 Answers
You could also try to do something like this:
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:
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 ); Just use an array:
var config.type = ["RED", "BLUE", "YELLO"]; config.type[0]; //"RED" Use an array ([]) instead of an object ({}), then flip the array to swap keys/values.
I suppose you could make a function that accepts an Array:
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.
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} Define the Enum:
var type = { RED: 1, BLUE: 2, YELLO: 3 }; get the color:
var myColor = type.BLUE; 
