Understand if the variable is valid

Question

What kind of control do you use to understand if the variable is valid
(not undefined, not null, not empty)?

Something like this :

hasAValue: function (value) {
return (("" !== value) && (null !== value) && ("undefined" !== typeof value) );
},

Answer 1

(value) produce already true or false, so:

if (value) { };

... is strictly equivaent to:

if hasValue(value) { }

The only difference being add a call to a function, a test, and context ( variables scope ), as much unnecessary time and memory requirement ^^

Answer 2

Yes, but order can be improved by:
- putting the typeof statement comparison at first, so if it is you don't need to perform others comparisons
- condensing your strict (not) equality tests of 'null' and 'undefined' into once not strict, which is equivalent

return ( (null != value) && ("" !== value) );

But you can simply test if the variable has a value which is NOT in:
- null
- undefined
- NaN
- 0
- false
-""
by:

return ( value );

Well, so... you don't need anymore of a function for that :P

Answer 3

like this :

hasAValue: function (value) {
if(value){
return true;
} else {
return false;
}
}