shorten javascript code - check if property exists and is not empty

Question

Is it possible to shorten this code?

var access_followup = user_access && user_access.followup && user_access.followup.access ? true : false;

Answer 1

Maybe I am answering the wrong thing, but why would you want to make it shorter? I'd vote to make it a bit longer, but easier to read for people who work with your code ( including you :) ).

You could make it more readable by splitting it up into multiple lines:

var access_followup = (
 user_access &&
 user_access.followup &&
 user_access.followup.access === true // if access is a boolean value
);

Or, in case you really really want to have short code and you do not use a minifier already, you can try https://jscompress.com/ (which actually compresses any code you paste into it! but makes it WAY less readable).

Answer 2

Unfortunately JS does not have a null conditional operator. You could write helper function for it or use a slightly less effective method of creating dummy objects:

var access_followup = !!((user_access || {}).followup || {}).access;

which is shorter and prevents using the property names more than once, but doesn't improve readability. The !! is used to enforce a boolean value even when the values don't exist

Answer 3

If the first 2 checks are because you are protecting against exception thrown when user_access.followup is undefined, you can try this:

var accessFollowup;
try {
  accessFollowup = !!user_access.followup.access;
} catch (e) {
  accessFollowup = false; 
}

You could also shorten by removing just the ternary by using !! to force last element into Boolean value:

var access_followup = !!user_access && !!user_access.followup && !!user_access.followup.access

Answer 4

very ugly code that works

var access_followup = (followup = (user_access || {}).followup) && followup.access;