isset
Check if an array item is set in JS
Use the in keyword to test if a attribute is defined in a object if (assoc_var in assoc_pagine) OR if (“home” in assoc_pagine) There are quite a few issues here. Firstly, is var supposed to a variable has the value “home”, “work” or “about”? Or did you mean to inspect actual property called “var”? If … Read more
PHP: Check if variable exist but also if has a value equal to something
Sadly that’s the only way to do it. But there are approaches for dealing with larger arrays. For instance something like this: $required = array(‘myvar’, ‘foo’, ‘bar’, ‘baz’); $missing = array_diff($required, array_keys($_GET)); The variable $missing now contains a list of values that are required, but missing from the $_GET array. You can use the $missing … Read more
Calling a particular PHP function on form submit
In the following line <form method=”post” action=”display()”> the action should be the name of your script and you should call the function, Something like this <form method=”post” action=”yourFileName.php”> <input type=”text” name=”studentname”> <input type=”submit” value=”click” name=”submit”> <!– assign a name for the button –> </form> <?php function display() { echo “hello “.$_POST[“studentname”]; } if(isset($_POST[‘submit’])) { display(); … Read more
PHP – Checking if array index exist or is null [duplicate]
The function array_key_exists() can do that, and property_exists() for objects, plus what Vineet1982 said. Thanks for your help.
What’s the difference between ‘isset()’ and ‘!empty()’ in PHP?
ISSET checks the variable to see if it has been set. In other words, it checks to see if the variable is any value except NULL or not assigned a value. ISSET returns TRUE if the variable exists and has a value other than NULL. That means variables assigned a “”, 0, “0”, or FALSE … Read more
Test if an argument of a function is set or not in R
You use the function missing() for that. f <- function(p1, p2) { if(missing(p2)) { p2=p1^2 } p1-p2 } Alternatively, you can set the value of p2 to NULL by default. I sometimes prefer that solution, as it allows for passing arguments to nested functions. f <- function(p1, p2=NULL) { if(is.null(p2)) { p2=p1^2 } p1-p2 } … Read more
is there something like isset of php in javascript/jQuery? [duplicate]
Try this expression: typeof(variable) != “undefined” && variable !== null This will be true if the variable is defined and not null, which is the equivalent of how PHP’s isset works. You can use it like this: if(typeof(variable) != “undefined” && variable !== null) { bla(); }