I am trying to convert a javascript code file to a typescript file, however, I have difficulties doing it when meeting to modify a function through the variable reference.
In javascript, the code was written as:
Object.getPrototypeOf(ctx).rounded_rect = function(){
}
where ctx
is a canvas rendering context 2d varibale
How do I convert this code to typescript code? When I copy and paste it to typescript file, it shows error saying Property 'rounded_rect' does not exist on type 'CanvasRenderingContext2D'.
Also, what is this line of code called?
You need to extend the native prototype which requires a declaration first:
declare global {
interface CanvasRenderingContext2D {
rounded_rect() : void;
}
}
After that you can implement it:
CanvasRenderingContext2D.prototype.rounded_rect = function(){
/*whatever*/
};
May refer to this similar answer...
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