TypeScript or JavaScript type casting

How does one handle type casting in TypeScript or Javascript?

Say I have the following TypeScript code:

module Symbology { 

    export class SymbolFactory { 

        createStyle( symbolInfo : SymbolInfo) : any { 
            if (symbolInfo == null)
            {
                 return null;
            }

            if (symbolInfo.symbolShapeType === "marker") {      

                // how to cast to MarkerSymbolInfo          
                return this.createMarkerStyle((MarkerSymbolInfo) symbolInfo);
            }                                  
        }

        createMarkerStyle(markerSymbol : MarkerSymbolInfo ): any { 
            throw "createMarkerStyle not implemented";
        }              

    }
}

where SymbolInfo is a base class. How do I handle typecasting from SymbolInfo to MarkerSymbolInfo in TypeScript or Javascript?

You can cast like this:

return this.createMarkerStyle( symbolInfo);

Or like this if you want to be compatible with tsx mode:

return this.createMarkerStyle(symbolInfo as MarkerSymbolInfo);

Just remember that this is a compile-time cast, and not a runtime cast.

Stack Overflow Q#13204759, score: 418