TypeScript template doesn't work in FireFox

If you're using Visual Studio 2012 and you've added the TypeScript for Microsoft Visual Studio 2012 extension then you will be able to jump start a TypeScript project using the template. If you click File > New > Project and look under the Visual C# templates you'll see a template called HTML Application with TypeScript. Selecting this template will generate a new project with a TypeScript file with the following contents:

class Greeter {
    element: HTMLElement;
    span: HTMLElement;
    timerToken: number;
   
    constructor (element: HTMLElement) {
        this.element = element;
        this.element.innerText += "The time is: ";
        this.span = document.createElement('span');
        this.element.appendChild(this.span);
        this.span.innerText = new Date().toUTCString();
    }

    start() {
        this.timerToken = setInterval(() =>
          this.span.innerText = new Date().toUTCString(), 500);
    }

    stop() {
        clearTimeout(this.timerToken);
    }
}

window.onload = () => {
    var el = document.getElementById('content');
    var greeter = new Greeter(el);
    greeter.start();
};

The problem with this code is the use of the .innerText property which is called .textContent in FireFox.

Here is a replacement to the above template that will work in FireFox and other browsers to get you moving forward again.

Tested on:
FireFox 16.0.2
Safari for Windows 5.1.7
IE9
Chrome 23.0.1271.64 m
Opera 12.10

class Greeter {
    element: HTMLElement;
    span: HTMLElement;
    timerToken: number;
    hasInnerText: bool;
   
    constructor (element: HTMLElement) {
        this.element = element;
        // Firefox uses textContent
        this.hasInnerText = !this.element.textContent;
        this.appendElementText(this.element, "The time is: ");
        this.span = document.createElement('span');
        this.element.appendChild(this.span);
        this.setElementText(this.span, new Date().toUTCString());
    }

    setElementText(elem: HTMLElement, value: string) {
        if (this.hasInnerText) {
            elem.innerText = value;
        } else {
            elem.textContent = value;
        }
    }

    appendElementText(elem: HTMLElement, value: string) {
        if (this.hasInnerText) {
            elem.innerText += value;
        } else {
            elem.textContent += value;
        }
    }

    start() {
        this.timerToken = setInterval(() =>
          this.setElementText(this.span, new Date().toUTCString()), 500);
    }

    stop() {
        clearTimeout(this.timerToken);
    }   
}

window.onload = () => {
    var el = document.getElementById('content');
    var greeter = new Greeter(el);
    greeter.start();
};