I seem to be using this test a lot
if( object && object !== "null" && object !== "undefined" ){
doSomething();
}
on objects I get back from a service call or from reading cookies (since different browsers return the different values null, undefined, "null", or "undefined").
Is there an easier/more efficient way of doing this check?
I don't think you can make that any simpler, but you could certainly refactor that logic into a function:
function isRealValue(obj)
{
return obj && obj !== 'null' && obj !== 'undefined';
}
Then, at least your code becomes:
if (isRealValue(yourObject))
{
doSomething();
}
If you have jQuery, you could use $.isEmptyObject().
$.isEmptyObject(null)
$.isEmptyObject(undefined)
var obj = {}
$.isEmptyObject(obj)
All these calls will return true. Hope it helps
if(!!object){
doSomething();
}
If object is truthy, we already know that it is not null or undefined (assuming that the string values are a mistake). I assume that a not null and not undefined test is wanted.
If so, a simple comparison to null or undefined is to compare != null.
if( object != null ){
doSomething();
}
The doSomething function will run only if object is neither null nor undefined.
"null" string, but that's hardly a common scenario, but it is more common to see the "undefined" string because of typeof foo === "undefined". So my answer tries to get at the core of what is usually wanted since the question doesn't seem to represent any common real world example.true result.Maybe like this:
var myObj = {};
var isEmptyObj = !Object.keys(myObj).length;
if(isEmptyObj) {
// true
} else {
maybe like this
if (typeof object !== "undefined" || object !== null)
// do something
instanceOf instead of instanceof). I'd stay away from that site if I were you.
This should work without any issue.
if(object){ // checks for null and undefined
doSomething();
}
The best way to check if an object is empty is by using a utility function like the one below.
create a function
function isEmpty(obj) {
for(var key in obj) {
if(obj.hasOwnProperty(key))
return false;
}
return true;
}
Use above function following way:-
So if you have an empty object, you can check whether it is empty by using the above function.
var myObj = {}; // Empty Object
if(isEmpty(myObj)) {
// Object is empty (Would return true in this example)
} else {
// Object is NOT empty
}
I think you could simplify a bit your logic with the following:
if (object != null && typeof(object) == "object") {
doSomething();
}
The main problem is that if you just check typeof(object) == "object", it will return true if object is null since null's type is "object". However, if you first check that object != null, you can be sure you are having something that is neither undefined nor null.
another simple way is
if (eval(object)) doSomething();
You can use eval to cast any type including string and be executed by javascript, here is eval documentation
If you want an Object, that is not an Array, and is not null, you might have to do some work, as all 3 will have the same typeof value.
if (
typeof maybeObject === 'object'
&& maybeObject !== null
&& !Array.isArray(maybeObject)) {
}
"null"and"undefined", then your method can't be any simpler."null"or"undefined". Thanks for the confirmation.!!likeif(!!myobj){doSomething();}to check the object. It converts the object to boolean and then inverts it again. Look at this answer for a very good explanation .