Variable Arguments Sometimes it makes sense for a mixin to take an unknown number of arguments. For example, a mixin for creating box shadows might take any number of shadows as arguments. For these situations, Sass supports “variable arguments,” which are arguments at the end of a mixin declaration that take all leftover arguments and … Read more
This is undefined behaviour. u.i and u.ch are located at the same memory address. So, the result of writing into one and reading from the other depends on the compiler, platform, architecture, and sometimes even compiler’s optimization level. Therefore the output for u.i may not always be 515. Example For example gcc on my machine … Read more
A slightly simpler way than your method is to use the Javascript in operator alert(‘x’ in o); // true alert(‘x’ in t); // false
array[index] == ‘undefined’ compares the value of the array index to the string “undefined”. You’re probably looking for typeof array[index] == ‘undefined’, which compares the type.
I like this: if (wlocation !== undefined) But if you prefer the second way wouldn’t be as you posted. It would be: if (typeof wlocation !== “undefined”)
The >= operator is essentially the negation of the < operator. And both invoke the Abstract Relational Comparison Algorithm which returns undefined for undefined >= undefined as defined in step 3 (a to c). Actually, you can also see that the greater-than(-or-equal) and less-than(-or-equal) operators are only meant to work with either numbers or strings. … Read more
If an object’s property may refer to some other object then you can test that for undefined before trying to use its properties: if (thing && thing.foo) alert(thing.foo.bar); I could update my answer to better reflect your situation if you show some actual code, but possibly something like this: function someFunc(parameterName) { if (parameterName && … Read more
1. Is getA1() implementation correct ? I feel it is incorrect as it is returning address of local variable or temporary. The only version of getAx() that is correct in your program is getA3(). Both of the others have undefined behaviour no matter how you use them later. 2. Which of the statements in main … Read more
If the variable is declared then: if (myvar === false) { will work fine. === won’t consider false to be undefined. If it is undefined and undeclared then you should check its type before trying to use it (otherwise you will get a reference error). if(typeof myvar === ‘boolean’ && myvar === false) { That … Read more
The first example doesn’t assign anything to the variable, so it implicitly refers to the undefined value (see 10.5 in the spec for the details). It is commonly used when declaring variables for later use. There is no need to explicitly assign anything to them before necessary. The second example is explicitly assigned null (which … Read more