Unable to instantiate typescript class in javascript

Question

I am sorry for potentially damn question.

Problem:

I've got the class defined in typescript as so:

1    class MyClass {
2        constructor() {
3            alert("MyClass instantiated!");
4        }
5    }
6    export = MyClass;

It's compiled into javascript as follows:

1    var MyClass = (function () {
2        function MyClass() {
3            var _this = this;
4            alert("MyClass instantiated!"); 
5        }
6    }
7    module.exports = MyClass

It is referenced from the jsp page - which also does the following:

<script language='javascript' src="myclass.js">
    var myclass = new MyClass();
</script>

Now, I've debugged it and it hits the line 1 (of compiled .js) and then exits at line number 7 of the same file.

Question:

Why doesn't it go in the function and exits? Am I instantiating it wrongly?

Any comments on why are there down votes?

Sasha
– Sasha

2016-04-08 14:42:22 +00:00
Commented Apr 8, 2016 at 14:42 — Sasha
– Sasha, Commented Apr 8, 2016 at 14:42

Dmitri Pavlutin · Accepted Answer · 2016-04-08 14:56:53Z

2

The problem is that you exported the TypeScript into a commonjs format (indicated by the module.exports = MyClass at line 7).
What you need is to compile the TypeScript into an UMD format, which can be accepted by the browser.
Or simply remove export = MyClass; from TypeScript source.

The working TS code:

class MyClass {
    constructor() {
        alert("MyClass instantiated!");
    }
}

will be compiled to:

var MyClass = (function () {
    function MyClass() {
        var _this = this;
        alert("MyClass instantiated!"); 
    }
}

Then use it on the page:

<script type="text/javascript" src="myclass.js"></script>
<script>
    var myclass = new MyClass();
</script>

edited Apr 8, 2016 at 14:56

answered Apr 8, 2016 at 14:41

Dmitri Pavlutin

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2 Comments

Sasha Over a year ago

Hi, thanks for your input, but the above doesn't suit eater. As I've simplified the class to indicate the problem, but the class I am struggling with is heavily used all over and acts as a starting point, therefore it needs the export, will try the umd solution.

Dmitri Pavlutin Over a year ago

@Sasha Try to export with --module umd

Naftali · Accepted Answer · 2016-04-08 14:41:49Z

0

You can't put context into a script tag that is loading another file.

Try this instead:

<script src="myclass.js"></script>
<script>
    var myclass = new MyClass();
</script>

edited Apr 8, 2016 at 14:41

answered Apr 8, 2016 at 14:41

Naftali

147k41 gold badges247 silver badges304 bronze badges

5 Comments

Naftali Over a year ago

See my updates... Also learn how to use JavaScript please :-)

Sasha Over a year ago

Hi, unfortunately not. Otherwise I would of course do so.

Sasha Over a year ago

I have compiled the class using umd format as well as separating context from the reference, continuing the research ...

Linard Arquint Over a year ago

@Sasha have you found out anything new in the meantime?

Sasha Over a year ago

No, done it a different way. Instantiating a class in .ts file rather.

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