関連ワード:  typescript string is null or undefined    typescript string is empty or undefined    typescript check if string is null or undefined    typescript string not null or undefined    typescript check string is not null or undefined    typescript string null or empty or undefined    typescript check if string is empty or undefined    typescript string not empty or undefined    typescript check if string is null empty or undefined    typescript check if string is not null or undefined or empty  
結果 : typescript string is null or undefined