How to store null values in var in javascript

Question

 var img2 = document.getElementById('ImgCorrectConditon2');//img2 = null
 img2.style.visibility = 'hidden';

If its a null. exception / error occurs and next line of codes not executing. How to stop executing line of code if any, control is null

Answer 1

try this code by checking img2 is not null

 var img2 = document.getElementById('ImgCorrectConditon2');//img2 = null
 if(img2 != null )
 {  
      img2.style.visibility = 'hidden';
 }

Answer 2

Simply check for null ?

if(img2 != null) {
   img2.style.visibility = 'hidden';
}