Essentials of Javascript - Cultural View

?: 56
?: in style guidelines
Some corporate programming guidelines list the use of the conditional operator as bad practice because it can harm
readability and long-term maintainability. Conditional operators are widely used and can be useful in certain
circumstances to avoid the use of an if statement, either because the extra verbiage would be too lengthy or because
the syntactic context does not permit a statement. For example:
#define MAX(a, b) (((a)>(b)) ? (a) : (b))
or
for (i = 0; i < MAX_PATTERNS; i++)
c_patterns[i].ShowWindow(m_data.fOn[i] ? SW_SHOW : SW_HIDE);
(The latter example uses the Microsoft Foundation Classes Framework for Win32.)
When properly formatted, the conditional operator can be used to write simple and coherent case selectors. For
example:
vehicle = arg == 'B' ? bus :
arg == 'A' ? airplane :
arg == 'T' ? train :
arg == 'C' ? car :
arg == 'H' ? horse :
feet;
Appropriate use of the conditional operator in a variable assignment context reduces the probability of a bug from a
faulty assignment as the assigned variable is stated just once as opposed to multiple times.
See also
• ?? Operator
References
[1] "BCPL Ternary operator (page 15)" (http://cm.bell-labs.com/cm/cs/who/dmr/bcpl.pdf). BCPL Reference Manual. .
[2] http://www.python.org/doc/faq/programming/#is-there-an-equivalent-of-c-s-ternary-operator