Functions:

Side Effects

• Side Effects are lies, promises one thing and does other hidden things unexpected changes to variable of its own class

Output Arguments

• Avoid using output arguments

Command Query Separation

• Function should either do something or ans something, but not both

Prefer exception to returning error code

• Returning error code and then handling the exception in function is not good idea when required immediate action

  if(deleteFile() === "OK") {
      if(deleteReference() == "OK")
  	    if(deleteAfterMath() == "OK")
     } else {
         console.log("Failed to delete")
     }
   //Instead
   try {
       deleteFile()
       deleteReference()
       deleteAfterMath()
   } catch (exception) {
       console.log("Failed to delete")
   }

Extract try catch blocks

Error Handling is one thing

• If try exists in function, it should be very first word in the function and that there should be nothing after the catch/finally blocks

The Error.java dependency magnet

Conclusion

• Functions are verbs to the and classes are nouns