Verify if object is null Javascript / Angularjs

Question

Here is my code:

function getMelhorBloco(tamanho){

    var blocoMelhor = {};
    var testeEntrouBloco = true;

            for(var i = 0; i < $scope.blocos.length; i++) {
                if($scope.blocos[i].estado == "Livre") {

                    if(tamanho < $scope.blocos[i].tamanhoTotal) {
                        if(testeEntrouBloco) {
                            blocoMelhor.indice = $scope.blocos[i].idBloco;
                            blocoMelhor.tamanho = $scope.blocos[i].tamanhoTotal;
                            testeEntrouBloco = false;
                        } else {
                            if($scope.blocos[i].tamanhoTotal < blocoMelhor.tamanho) {
                                blocoMelhor.indice = $scope.blocos[i].idBloco;
                                blocoMelhor.tamanho = $scope.blocos[i].tamanhoTotal;

                            }
                        }
                    }
            }
        }

    return blocoMelhor;
}

I was trying to check if my object "blocoMelhor" is null.

I tried

if(blocoMelhor == null){} 
if(blocoMelhor == undefined){} 
if(blocoMelhor ===null){}

and the method:

function isEmpty(obj){
    for(var key in obj) {
        if(obj.hasOwnProperty(key)){
            return false;
        }
        return true;
    }
}

I printed the value of "blocoMelhor" and the console gives me this: Object { }

Any suggestions?

Why would you think that your object would be null? You're initializing it to `{}` - that's an empty object, but it's definitely not null or undefined. — Sam Hanley, May 13 '16 at 17:52
`isEmpty(obj)` will never return false because `keys in obj` gets a list of keys, meaning that the object MUST contain each one — , May 13 '16 at 17:53
Possible duplicate of [How do I test for an empty JavaScript object?](http://stackoverflow.com/questions/679915/how-do-i-test-for-an-empty-javascript-object) — jmargolisvt, May 13 '16 at 17:56

score 1 · Answer 1 · answered May 13 '16 at 17:53

1

try following

var blocoMelhor;

if(!blocoMelhor){ 
do something for null
}

initialization by {} means you create a object

answered May 13 '16 at 17:53

Jahirul Islam Bhuiyan

811
6
14

score 0 · Answer 2 · answered May 13 '16 at 17:54

0

have you tried to use something like

if (!blocoMelhor){ //do something }

? it's the best way, I think.

answered May 13 '16 at 17:54

alvarosps

83
1
9

`{}` will return true; – Brian Glaz May 13 '16 at 17:55

score 0 · Accepted Answer · answered May 13 '16 at 18:07

0

i made the verification with the attributes of object and works:

var returnOfGetMelhorBloco = getMelhorBloco(tamanho);
if(returnOfGetMelhorBloco.indice == undefined){
//the object is null
} else {
//the object is not null
}

answered May 13 '16 at 18:07

F Matheus

25
1
8

Verify if object is null Javascript / Angularjs

3 Answers3