Accessing "pseudo-globals" by their name as a string
I am now in the process of removing most globals from my code by enclosing everything in a function, turning the globals into "pseudo globals," that are all accessible from anywhere inside that function block.
(function(){
var g = 1;
var func f1 = function () { alert (g); }
var func f2= function () { f1(); }
})();
(technically this is only for my "release version", where I append all my files together into a single file and surround them with the above....my dev version still has typically one global per js file)
This all works great except for one thing...there is one important place where I need to access some of these "globals" by string name. Previously, I could have done this:
var name = "g";
alert (window[name]);
and it did the same as
alert(g);
Now -- from inside the block -- I would like to do the same, on my pseudo-globals. But I can't, since they 开发者_运维百科are no longer members of any parent object ("window"), even though are in scope.
Any way to access them by string?
Thanks...
Basically no, as answered indirectly by this question: Javascript equivalent of Python's locals()?
Your only real option would be to use eval, which is usually not a good or even safe idea, as described in this question: Why is using the JavaScript eval function a bad idea?
If the string name of those variables really and truly is defined in a safe way (e.g. not through user-input or anything), then I would recommend just using eval
. Just be sure to think really long and hard about this and whether there is not perhaps a better way to do this.
You can name the function you are using to wrap the entire code.
Then set the "global" variable as a member of that function (remember functions are objects in JavaScript).
Then, you can access the variable exactly as you did before....just use the name of the function instead of "window".
It would look something like this:
var myApp = new (function myApp(){
this.g = "world";
//in the same scope
alert ( "Hello " + this["g"]);
})();
//outside
alert ( "Hello " + myApp["g"]);
if you want to access something in a global scope, you have to put something out there. in your case it's probably an object which references your closed off function.
var obj1 = new (function(){
var g = 1;
var func f1 = function () { alert (g); }
var func f2= function () { f1(); }
})();
you can add a method or property as a getter for g
. if the value of g
isn't constant you might do like
this.getG = function() { return g; };
you can work from there to access items by name, like
alert( obj1["getG"]() );
alert( window["obj1"]["getG"]() );
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