if(variablename.value == “”) {
var variablename = “whatever”
}

Works for me.

- Juddling

string

in the head section just put var string;

then when you want to check the contents and see if it filled successfully,

do: if (string.length) { } because string.length will return 0 which is false, and will return a number greater then 1 (which is true) if the variable has any text whatsoever in it, and works the same for an array, but will return the number of array elements inside not letters. enjoy

Also, isset(‘varname’) will always return true, as it is set in the isset() function, and so is not properly tested (what if it was set in the test() function?).

Or am I missing something?

function isset(varname) { return eval(‘typeof(‘ + varname + ‘) != “undefined”‘); }

var1 = ‘test’; // global var

function test()
{
var var2 = ‘test’; // local var
alert(‘var1 isset() = ‘ + isset(‘var1′)); // true; global var
alert(‘var2 isset() = ‘ + isset(‘var2′)); // false; local var
alert(‘varname isset() = ‘ + isset(‘varname’)); // true; local var to isset()
alert(‘arguments[0] isset() = ‘ + isset(‘arguments[0]‘)); // true; local var to isset()
}

test();

Assumptions based on tests:

typeof(window[varname]) != ‘undefined’); can see only global scope, and gives no error
typeof(eval(varname) != ‘undefined’); can see local scope of isset(), but gives an error if not defined
eval(‘typeof(‘ + varname + ‘) != “undefined”‘); can see local scope of isset(), and gives no errors

All of these scripts use one of the two, which can only access vars within the scope of the function.
This includes local vars in isset() ie. varname, arguments[0] and global vars.

This would be useful for testing argument input in functions.
Yes, I can write out if(typeof(var1) != ‘undefined’) each time but I’m lazy.
I’m also a PHP programmer and would like to use one set of terminology.

function isset(variable_name)
{
try
{
if (typeof(eval(variable_name)) != ‘undefined’)
if (eval(variable_name) != null)
return true;
} catch(e) { }

return false;
}

variable_name is a string param

that was exactly what i needed