or-operator
Logical operator || in javascript, 0 stands for Boolean false?
|| — expr1 || expr2 (Logical OR) Returns expr1 if it can be converted to true; otherwise, returns expr2. Thus, when used with Boolean values, || returns true if either operand is true; if both are false, returns false.. && — expr1 && expr2 (Logical AND) Returns expr1 if it can be converted to false; … Read more
Shortcut “or-assignment” (|=) operator in Java
The |= is a compound assignment operator (JLS 15.26.2) for the boolean logical operator | (JLS 15.22.2); not to be confused with the conditional-or || (JLS 15.24). There are also &= and ^= corresponding to the compound assignment version of the boolean logical & and ^ respectively. In other words, for boolean b1, b2, these … Read more
JavaScript OR (||) variable assignment explanation
See short-circuit evaluation for the explanation. It’s a common way of implementing these operators; it is not unique to JavaScript.
Logical Operators, || or OR?
There is no “better” but the more common one is ||. They have different precedence and || would work like one would expect normally. See also: Logical operators (the following example is taken from there): // The result of the expression (false || true) is assigned to $e // Acts like: ($e = (false || … Read more
What does “var FOO = FOO || {}” (assign a variable or an empty object to that variable) mean in Javascript?
Your guess as to the intent of || {} is pretty close. This particular pattern when seen at the top of files is used to create a namespace, i.e. a named object under which functions and variables can be created without unduly polluting the global object. The reason why it’s used is so that if … Read more
Boolean operators && and ||
The shorter ones are vectorized, meaning they can return a vector, like this: ((-2:2) >= 0) & ((-2:2) <= 0) # [1] FALSE FALSE TRUE FALSE FALSE The longer form evaluates left to right examining only the first element of each vector, so the above gives ((-2:2) >= 0) && ((-2:2) <= 0) # [1] … Read more
What does the construct x = x || y mean?
It means the title argument is optional. So if you call the method with no arguments it will use a default value of “Error”. It’s shorthand for writing: if (!title) { title = “Error”; } This kind of shorthand trick with boolean expressions is common in Perl too. With the expression: a OR b it … Read more
JavaScript OR (||) variable assignment explanation
See short-circuit evaluation for the explanation. It’s a common way of implementing these operators; it is not unique to JavaScript.