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