Once I was working on an AngularJS application. I have a requirement
that under ng-repeat I need one object value with comma separated but ‘.’ in
last. We can achieve this with the help of ternary operator very easily, but I
found something different. This is like
{{ !$last
&& ', ' || '.'}}
The above
solution resolved the problem also, but the interesting thing is that who it is
working. It creates a confusion in my mind. Now I started to find out the best
answer for this. In-order to this I created a question on stackoverflow
and got many answers all are same. Every explain that it is working as a
Ternary operator.
It is a form of ternary operator.
&&
returns first operand if it is a falsy value and second operand if first
operand is truthy e.g. 1 && 3
will return 3
but 0 && 3
will return 0
. Second operator is not evaluated if
first is falsy. ||
is
similar but returns first operand if it is truthy and second operand if first
is falsy.
So basically
For readability reasons you should always prefer ternary operator cond && val1 ||
val2
is equivalend to cond ?
val1 : val2
under condition that val1
is truthy value. If this is not the case e.g. cond && 0 || 1
this will always
return last value 1
in this
case.?:
than Boolean shortcircuting
operators.
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