Embed a Conditional in a Conditional?

1

Since the and operator exists, is there any reason to embed a conditional in another conditional?

2

Can you give an example of what you mean?

3 
if (a ===0){
     if (b === 1){
         if (c===2){
             if (d ===3){ 
                   drawSun();
             }
          }
     }
}

Should an if-statement never be inside any if-statement?

4

It depends upon what logic you need to express. I nest logic all the time