How do I test for an empty JavaScript object?

After an AJAX request, sometimes my application may return an empty object, like:

var a = {};

How can I check whether that's the case?

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Answer

ECMA 7+:

// because Object.keys(new Date()).length === 0;
// we have to do some additional check
Object.entries(obj).length === 0 && obj.constructor === Object

ECMA 5+:

// because Object.keys(new Date()).length === 0;
// we have to do some additional check
Object.keys(obj).length === 0 && obj.constructor === Object

Pre-ECMA 5:

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

    return JSON.stringify(obj) === JSON.stringify({});
}

jQuery:

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jQuery.isEmptyObject({}); // true

lodash:

_.isEmpty({}); // true

Underscore:

_.isEmpty({}); // true

Hoek

Hoek.deepEqual({}, {}); // true

ExtJS

Ext.Object.isEmpty({}); // true

AngularJS (version 1)

angular.equals({}, {}); // true

Ramda

R.isEmpty({}); // true

[출처] https://stackoverflow.com/questions/679915/how-do-i-test-for-an-empty-javascript-object