Top "Variables" questions

How can I determine if a variable is 'undefined' or 'null'?

How do I determine if variable is undefined or null? My code is as follows: var EmpName = $("div#esd-names div#…

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"Notice: Undefined variable", "Notice: Undefined index", and "Notice: Undefined offset" using PHP

I'm running a PHP script and continue to receive errors like: Notice: Undefined variable: my_variable_name in C:\wamp\…

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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, …

javascript variables initialization undefined

How do JavaScript closures work?

How would you explain JavaScript closures to someone with a knowledge of the concepts they consist of (for example functions, …

javascript function variables scope closures

How to check if a variable is set in Bash?

How do I know if a variable is set in Bash? For example, how do I check if the user …

bash shell variables

How to trim whitespace from a Bash variable?

I have a shell script with this code: var=`hg st -R "$path"` if [ -n "$var" ]; then echo $var fi …

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How can I print variable and string on same line in Python?

I am using python to work out how many children would be born in 5 years if a child was born …

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How to check a not-defined variable in JavaScript

I wanted to check whether the variable is defined or not. For example, the following throws a not-defined error alert( …

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How do I check if a variable exists?

I want to check if a variable exists. Now I'm doing something like this: try: myVar except NameError: # Do something. …

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Define global variable in a JavaScript function

Is it possible to define a global variable in a JavaScript function? I want use the trailimage variable (declared in …

javascript function variables scope declaration