Checking if a variable is not null
5374
How to check if a macro value is empty or will not create text with plain TeX conditionals?
72088
Why shouldn't we allow NULLs?
62074
Which is more effective: if (null == variable) or if (variable == null)?
24759
How do I use the conditional (ternary) operator?
36270
Nullable type issue with ?: Conditional Operator
576
How can I check for an empty/undefined/null string in JavaScript?
128709
Why is there a `null` value in JavaScript?
79162
Javascript null or empty string does not work
144361
string.IsNullOrEmpty(string) vs. string.IsNullOrWhiteSpace(string)
38241
How do I check for nulls in an '==' operator overload without infinite recursion?
90161
What does [param: NotNull] mean in C#?
93772
Why is isNaN(null) == false in JS?
25703
Best way to test for a variable's existence in PHP; isset() is clearly broken
123797
Not equal  != operator on NULL
63372
see if a variable equals any other variables in a list php
146642
Using an if statement to check if a div is empty
90853
How can I compare multiple variables to a single condition?