How to check ‘undefined’ value in jQuery
Possible Duplicate: Detecting an undefined object property in JavaScript javascript undefined compare How we can add a check for an undefined variable, like: … Read more
undefined
What are all the common undefined behaviours that a C++ programmer should know about? [closed]
It’s difficult to tell what is being asked here. This question is ambiguous, vague, incomplete, overly broad, or rhetorical and cannot be reasonably … Read more
“undefined” function declared in another file?
I’m trying to write a basic go program that calls a function on a different file, but a part of the same package. … Read more
Test if something is not undefined in JavaScript
I’m checking if(response[0].title !== undefined), but I get the error: Uncaught TypeError: Cannot read property ‘title’ of undefined. 11 Answers 11
How to check if a JavaScript variable is NOT undefined? [duplicate]
This question already has answers here: JavaScript check if variable exists (is defined/initialized) (31 answers) Closed 6 years ago. Things I’ve tried that … Read more
Set a variable if undefined in JavaScript
I know that I can test for a JavaScript variable and then define it if it is undefined, but is there not some … Read more
Can I set variables to undefined or pass undefined as an argument?
I’m a bit confused about JavaScript’s undefined and null values. What does if (!testvar) actually do? Does it test for undefined and null … Read more
Check if object exists in JavaScript
How do I verify the existence of an object in JavaScript? The following works: if (!null) alert(“GOT HERE”); But this throws an Error: … Read more
variable === undefined vs. typeof variable === “undefined”
The jQuery Core Style Guidelines suggest two different ways to check whether a variable is defined. Global Variables: typeof variable === “undefined” Local … Read more
JavaScript check if variable exists (is defined/initialized)
Which method of checking if a variable has been initialized is better/correct? (Assuming the variable could hold anything (string, int, object, function, etc.)) … Read more