The assignment is hardly a performance concern in modern javascript. I imagine if we set up a jsperf test case we would find the difference negligible and the o

The assignment is hardly a performance concern in modern javascript. I imagine if we set up a jsperf test case we would find the difference negligible and the ops/s in the 10s of millions range. This is not the kind of thing that slows down JS apps. I could see, using the if statement form, that you might have a programmer decide to compact it and drop the brackets - and then you might fall in the trap where somebody thinks they're in an if block when they're really not. Happens pretty often. In addition, I don't know if you really would want to check for null. I usually just check for undefined, which would be the absence of any provided value (as opposed to a provided value that just happens to be null). Of course, it depends on the app. In addition, I really don't like using short-circuited boolean ops for assignment. The style is grating to me - it's not immediately obvious what it's really doing. To each his own. EDIT: Created a simple jsperf test. Difference is about 6.8%, but we're talking hundreds of millions of ops/s. Not the kind of stuff that matters outside of raw benches. http://jsperf.com/ternary-vs-if-for-default-args http://jsperf.com/ternary-vs-if-for-default-args