如何使用Typescript的外部模块动态实例化

Question

We started using requirejs for our project and converting all our internal modules to external modules.

I'm having problems dynamically instanciating classes. We need to be able to instanciate classes using a simple dot notation string.

When all our modules were internal, they were accessible through the window object. Here's an example :

// file - TestAction.ts
module cb.action {
    export class TestAction {
        constructor() {}
    }
}

Using the following function with className = "cb.action.TestAction" we could easily get a TestAction instance.

var instantiateByName = function (className) {
    "use strict";
    var ClassName2 = className.split('.').reduce(function (current, name) {
        return current[name];
    }, window);
    return new ClassName2();
    };

Now that we changed all our modules to external modules the TestAction.ts file now looks like this :

// file - TestAction.ts
export class TestAction {
    constructor() {}
}

2 main problems : - Depending on the dot notation string I'm receiving, I need to import a different file. ( dynamically require a file ) - I need an equivalent to the instantiateByName function above since I can't use the window object anymore.

Looking forward to having your inputs

Answer 1

I would slightly change the module structure (if you are using one class per file...)

class TestAction {
    constructor() {}
}

export = TestAction;

And then instead of using a method to dynamically load modules by name, you can use RequireJS iteself to do it...

// Instead of 'instantiateByName'...
import TestAction = require('./action/TestAction');
var myAction = new TestAction();

This is compiled into the following...

define(["require", "exports", './action/TestAction'], function(require, exports, TestAction) {
    var myAction = new TestAction();
});

And this handles the fact that RequireJS loads the script file asynchronously.