is it possible to do something like this without evil eval:
var str='MyClass';
eval('new '+str);
i just learned that there's ReflectionClass in PHP... thanks.
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2 Answers
You could try this:
var str = "MyClass";
var obj = new window[str];
Here's an example:
function MyClass() {
console.log("constructor invoked");
}
var s = "MyClass";
new window[s]; //logs "constructor invoked"
1 Comment
kubi
perfect, thanks! EDIT: ooh, and I can put the class definitions into an object, instead of using the window object...
Create object (invoke constructor) via reflection:
SomeClass = function(arg1, arg2) {
// ...
}
ReflectUtil.newInstance('SomeClass', 5, 7);
and implementation:
/**
* @param strClass:
* class name
* @param optionals:
* constructor arguments
*/
ReflectUtil.newInstance = function(strClass) {
var args = Array.prototype.slice.call(arguments, 1);
var clsClass = eval(strClass);
function F() {
return clsClass.apply(this, args);
}
F.prototype = clsClass.prototype;
return new F();
};
answered Aug 4, 2011 at 19:09
Mykhaylo Adamovych
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3 Comments
Elliot B.
It's only bad if you do not properly validate the string being
evaled. Aside from that, this answer is great. The currently accepted answer only works if the class is globally accessible (i.e., at the window level). Classes defined within closures, for instance, cannot be instantiated using the window method.
Jacob Relkin
@ElliotB. In that case, you can use
this to reference the current scope. a la new this[className]Elliot B.
@JacobRelkin That doesn't appear to work. I constructed a test with scope referenced in a couple different ways: jsfiddle.net/d84bh/1 It only works for me when the class is defined at the global/window level: jsfiddle.net/d84bh/2