javascript - JS IF Else And syntax

Question

Have looked on google and w3schools, but can't find an solution to my question.

If I have two values A and B, how will the JS IF syntax then look like if:

• Do condition if Only A is filled
• Do condition if Only B is filled
• Do condition if both A AND B is filled
• Else do condition if non are filled

Answer 1

You start with the most specific first since the logic starts from the top to the bottom of the list. In this case you would need to check for both A and B to start, followed by the other checks which do not depend on multiple conditions.

if (A && B) {}
else if (A || B) {}
else {}

if you need to know difference between A and B

if (A && B) {}
else if (A) {}
else if (B) {}
else {}