Ternary

Use a single line to define a variable using if/ else logic.

CONDITIONAL_EXPRESSION ? VALUE_IF_TRUTHY : VALUE_IF_FALSY

Example:

var x = 0
var y = 10

x ? "yes" || "no"
// "no"
y ? "yes" : "no"
// "yes"

Or using an expression.

y > 5 ? "y is big" : "y is small"
y > 5 ? y : x

This syntax is the same as in C.

In Python:

x = 0
y = 10

answer = "yes" if x else "no"
# "no"
answer = "yes" if y else "no"
# "yes"

AND OR

You can use && and || operators for the same effect as above, though it is is less readable.

var x = 0
var y = 10

x && "yes" || "no"
// "no"
y && "yes" || "no"
// "yes"

You’ll find the same thing in shell programming.

./script.sh && echo 'Success' || echo 'Failed'

OR

Use the logical OR operation (||) to use a default value if the value (like a boolean, string or number) is a null value.

var x = 0
x = x || 123
// 123

var y = 10
y = y || 123
// 10

Some languages like Ruby let you do this in a shorter expression:

x ||= 123
# i.e.
x = x || 123