Navigator.screenshot is always undefined

i’m using https://github.com/gitawego/cordova-screenshot#usage-in-angularjs plugin…
and when I come to save screenshot using code below,

navigator.screenshot.save(function(error,res){
                if(error){
                    
                  console.error(error);
                }else{
                  console.log('ok',res.filePath);
                }
              });

it has error saying navigator.screenshot is undefined…
when I console.log navigator it says as below , I can’t find screenshot object.