JavaScript: how-to conditional function call on common arguments

While reading the source code of ImageDiff - a JavaScript library for calculating diff between images,

I came across a technique for

conditionally calling one function or another, on the same argument passed to whichever function

. 

Here's the snippet:

(x ? alert : prompt) ('hi')

The value of x determines whether alert('hi') or prompt('hi') will be called. Both functions are passed with ('hi').

I hope you'll find this snippet useful when you need to

conditionally decide what function to call, on the same arguments.