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'0' in any case is considered as false value, so when you pass 0 as an argument like: if(0) { ---statments--- } The statement part of will not get executed, and the system will directly jump to else part.
Definition and Usage. The if/else statement executes a block of code if a specified condition is true. If the condition is false, another block of code can be executed. The if/else statement is a part of JavaScript's "Conditional" Statements, which are used to perform different actions based on different conditions.
A nested if statement is an if statement placed inside another if statement. Nested if statements are often used when you must test a combination of conditions before deciding on the proper action.
The short answer here is that you've written illegible code that you can no longer read. A few things to consider: (1) Use more, smaller, well-named functions (2) Use meaningful variable names (3) Make if statements that read like english.
This can be useful if there are #if statements, ala
if (0)
{
// Empty block
}
#if TEST1_ENABLED
else if (test1())
{
action1();
}
#endif
#if TEST2_ENABLED
else if (test2())
{
action2();
}
#endif
etc.
In this case, any (and all) of the tests can be #if'ed out, and the code will compile correctly. Almost all compilers will remove the if (0) {} part.
A simple autogenerator could generate code like this, as it is slightly easier to code - it doesn't have to consider the first enabled block separately.
I sometimes use this for symmetry so I can move the other else if{ freely around with my editor without having to mind the first if.
Semantically the
if (0) {
// Empty braces
} else
part doesn't do anything and you can count on optimizers to delete it.
I've seen a similar pattern used in generated code. For example, in SQL, I've seen libraries emit the following where clause.
where 1 = 1
This presumably makes it easier to just add on other criteria, because all additional criteria can be prepended with and instead of an additional check to see if it is the first criteria or not.
As written, the if (0) {} clause compiles out to nothing.
I suspect the function of the clause at the top of this ladder is to provide an easy place to temporarily disable all the other functionality at once (for debugging or comparison purposes) by changing the 0 to a 1 or true.
I am not sure of any optimizations, but my two cents:
This happened because of some code modification, where one primary condition was removed, (the function call in initial if block, let's say), but the developers/ maintainers
if-else blockso instead of removing the associated if block, they simply changed the condition to if(0) and moved on.
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