TypeScript: problems with type system

Question

I\'m just testing typescript in VisualStudio 2012 and have a problem with its type system. My html site has a canvas tag with the id \"mycanvas\". I\'m trying to draw a rect

Answer 1

I had the same problem, but with SVGSVGElement instead of HTMLCanvasElement. Casting to SVGSVGElement gave a compile-time error:

var mySvg = document.getElementById('mySvg');

Cannot convert 'HTMLElement' to 'SVGSVGElement':
Type 'HTMLElement' is missing property 'width' from type 'SVGSVGElement'.
Type 'SVGSVGElement' is missing property 'onmouseleave' from type 'HTMLElement'.

If fixed it by first casting to 'any':

var mySvg = document.getElementById('mySvg');

or this way (it has the identical effect)

var mySvg: SVGSVGElement = document.getElementById('mySvg');

Now mySvg is strongly typed as SVGSVGElement.