Dynamically Instantiate a Dojo Class At Runtime
Need to create an instance of a class in Dojo without knowing what that class is ahead of time? Will you only have the name of the class that you want to instantiate? Check this out:
/**
* Create a new instance of a Dojo class.
*
* @param className
* (String) A fully-qualified name for class, such as
* "my.pack.age.Class"
* @param constructorSettings
* (object) An object that will be passed on to the
* class's constructor.
*/
function instantiateDojoClass(className, constructorSettings){
try {
dojo.require(className);
/*
* Eval the class name to get a reference to the
* function, then call it as a constructor using the
* constructorSettings object as an argument.
*/
var obj = new (eval(className))(constructorSettings);
} catch (e){
/*
* Handle any errors that might happen.
*/
if(console){
console.error("Could not instantiate %s: %s", classsName, e.message);
} else {
alert("Could not instantiate "+className+": "+e.message);
}
throw e;
}
}The real trickery here is in the line:
var obj = new (eval(className))(constructorSettings);This evaluates the string className to retrieve a reference to the dojo function that was ‘created’ by the call to dojo.require(..), then calls that function as a constructor by using the new keyword. It passes the constructorSettings object on to the constructor, just like you’d do with any normal dojo instantiation.
