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
– Sam Hanley, Commented May 13, 2016 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 — user3786755
– user3786755, Commented May 13, 2016 at 17:53
Possible duplicate of How do I test for an empty JavaScript object? — jmargolisvt
– jmargolisvt, Commented May 13, 2016 at 17:56

Jahirul Islam Bhuiyan · Accepted Answer · 2016-05-13 17:53:14Z

1

try following

var blocoMelhor;

if(!blocoMelhor){ 
do something for null
}

initialization by {} means you create a object

answered May 13, 2016 at 17:53

Jahirul Islam Bhuiyan

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Comments

alvarosps · Accepted Answer · 2016-05-13 17:54:02Z

0

have you tried to use something like

if (!blocoMelhor){ //do something }

? it's the best way, I think.

answered May 13, 2016 at 17:54

alvarosps

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1 Comment

Brian Glaz Over a year ago

{} will return true;

F Matheus · Accepted Answer · 2016-05-13 18:07:12Z

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, 2016 at 18:07

F Matheus

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