How do I handle TypeScript casting in TypeScript or JavaScript?

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1

How do I handle TypeScript casting in TypeScript or JavaScript?

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 do I cast to MarkerSymbolInfo in TypeScript?
                return this.createMarkerStyle((MarkerSymbolInfo) symbolInfo);
            }                                  
        }

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

Where SymbolInfo is a base class. How do I handle casting from SymbolInfo to MarkerSymbolInfo in TypeScript or JavaScript? What is the correct approach for TypeScript casting in this context?

2

Hi

In TypeScript, you can cast an object to a specific type using type assertion. This is similar to the (Type) object syntax in other languages. To cast symbolInfo to MarkerSymbolInfo, you can use the following approach:

return this.createMarkerStyle(symbolInfo as MarkerSymbolInfo);

This tells TypeScript that you are confident that symbolInfo is of type MarkerSymbolInfo, and it allows you to pass it to the createMarkerStyle method. This is the most common and straightforward approach for TypeScript casting.