Is a reversed switch statement acceptable JavaScript?
JSLint is complaining that (true)
is a weird condition
. Which is understandable if I wasn't using it on a reversed switch statement. So is JSLint wrong or should I not be using reversed switch statements?
Thanks for any help/enlightenment.
switch (true) {
case (menuLinksLength < 4):
numberOfColumns = 1;
break;
case (menuLinksLength >开发者_开发百科; 3 && menuLinksLength < 7):
numberOfColumns = 2;
break;
case (menuLinksLength > 6 && menuLinksLength < 10):
numberOfColumns = 3;
break;
case (menuLinksLength > 9):
numberOfColumns = 4;
break;
default:
numberOfColumns = 0;
}
Personally I wouldn't like seeing reversed switch
in a code base. It doesn't buy you anything when compared to a plain if/elseif
block, and its exotic nature can be cause for confusion.
That's also what JSLint is complaining about:
You are doing something unorthodox. Is there a good reason for it? If not, it might be better to stick to the basics.
The third edition of the ECMA-262 standard (supported by Firefox 1.0+, Google Chrome 1.0+, MSIE 5.5+ and others) defines that
switch (expression) {
case label1:
statements1
.
.
.
}
executes statements1
if (expression)
matches label1
.
That means that your switch
statement is perfectly fine.
I tried it out on Firefox, Chrome and IE. None complains...
Edit:
Now the guessing part:
JSLint is a code anaylisis tool. When it sees switch (true)
, it assumes that you don't know what you're doing. Weird doesn't mean necessarily wrong...
numberOfColumns = Math.max(4, Math.floor(menuLinksLength / 3));
This will give you identical results to your existing code. Your question is fairly ambiguous, as "acceptable" is a very subjective term. I would personally reject any merge request with a reversed switch statement, because I actually can't think of a situation where that couldn't be replaced with something simpler and/or easier to read.
Whether or not a "reverse switch" is considered good practice in javascript depends on the specific use case.
In general, a reverse switch can make the code more readable and maintainable by clearly defining the intended behaviour for cases that don't match a specific pattern. This can be useful in situations where you want to catch all edge cases or exceptions that are not explicitly defined in the switch statement.
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