How do I make JavaScript Object using a variable String to define the class name?
Here's a more robust solution that will work with namespaced functions:
var stringToFunction = function(str) {
var arr = str.split(".");
var fn = (window || this);
for (var i = 0, len = arr.length; i < len; i++) {
fn = fn[arr[i]];
}
if (typeof fn !== "function") {
throw new Error("function not found");
}
return fn;
};
Example:
my = {};
my.namespaced = {};
(my.namespaced.MyClass = function() {
console.log("constructed");
}).prototype = {
do: function() {
console.log("doing");
}
};
var MyClass = stringToFunction("my.namespaced.MyClass");
var instance = new MyClass();
instance.do();
BTW: window is the reference to the global Object in browser JavaScript. Which is also this
, and should work even in non-browser environments such as Node.js, Chrome extensions, transpiled code etc.
var obj = new this[classNameString]();
The limitation is that the class being called must be in the global context. If you want to apply the same to a scoped class you need to do:
var obj = (Function('return new ' + classNameString))()
However, there really is no reason to use a string. JavaScript functions are themselves objects, just like strings which are objects also.
Edit
Here is a better way to get the global scope that works in strict mode as well as non-browser JS environments:
var global;
try {
global = Function('return this')() || (42, eval)('this');
} catch(e) {
global = window;
}
// and then
var obj = new global[classNameString]
From: How to get the global object in JavaScript?
If MyClass is global, you can access it as a property of window object (assuming your code runs in a browser) using subscript notation.
var myObject = new window["MyClass"]();
Would it work if you did something like this:
var myObject = window[classNameString];
..?