_.isEmpty(obj, true)
var obj = {
'firstName': undefined
, 'lastName' : undefined
};
console.log(_.isEmpty(obj)); // false
console.log(_.isEmpty({})); // true<script src="https://cdnjs.cloudflare.com/ajax/libs/lodash.js/4.17.4/lodash.js"></script>Please, see http://www.ericfeminella.com/blog/2012/08/18/determining-if-an-object-is-empty-with-underscore-lo-dash/
Answer from Armen Zakaryan on Stack Overflow_.isEmpty(obj, true)
var obj = {
'firstName': undefined
, 'lastName' : undefined
};
console.log(_.isEmpty(obj)); // false
console.log(_.isEmpty({})); // true<script src="https://cdnjs.cloudflare.com/ajax/libs/lodash.js/4.17.4/lodash.js"></script>Please, see http://www.ericfeminella.com/blog/2012/08/18/determining-if-an-object-is-empty-with-underscore-lo-dash/
Your example object is not empty so instead perhaps you want to test if all properties are undefined
let o = {foo: undefined};
!_.values(o).some(x => x !== undefined); // true
Videos
» npm install lodash.isempty
if(user) will pass for empty Object/Array, but they are empty and should be rejected.
Also if(user) will fail for values like 0 or false which are totally valid values.
Using isEmpty() will take care of such values. Also, it makes code more readable.
Point to note is isEmpty(1) will return true as 1 is a primitive value and not a data structure and hence should return true.
This has been stated in Docs:
Checks if value is an empty object, collection, map, or set.
Also as per docs,
Objects are considered empty if they have no own enumerable string keyed properties.
So if you have an object which does not have non-enumerable properties, its considered as empty. In the below example, foo is a part of object o and is accessible using o.foo but since its non-enumerable, its considered as empty as even for..in would ignore it.
var o = Object.create(null);
Object.defineProperty(o, "foo", {
enumerable: false,
value: "Hello World"
})
Object.defineProperty(o, "bar", {
enumerable: false,
value: "Testing 123"
});
console.log(o)
for (var k in o) {
console.log(k)
}
console.log(o.foo)
console.log(_.isEmpty(o))<script src="https://cdnjs.cloudflare.com/ajax/libs/lodash.js/4.17.4/lodash.min.js"></script>Note: This does not mean you should use lodash for such purpose. You can write your own isEmpty function.
Following is something that I use:
This will return true for following cases:
{},[],"",undefined,null, object in above snippet(no enumerable property)
function isEmpty(value){
return value === undefined ||
value === null ||
(typeof value === "object" && Object.keys(value).length === 0) ||
(typeof value === "string" && value.trim().length === 0)
}
Simple and elegant function for checking the values are empty or not
function isEmpty(value) {
const type = typeof value;
if ((value !== null && type === 'object') || type === 'function') {
const props = Object.keys(value);
if (props.length === 0 || props.size === 0) {
return true;
}
}
return !value;
}
Testing the above method
It will return 'true' for all cases below
console.log(isEmtpy(null))
console.log(isEmtpy(0))
console.log(isEmtpy({}))
console.log(isEmtpy(new Set())
console.log(isEmtpy(Object.create(null))
console.log(isEmtpy(''))
console.log(isEmtpy(() => {}))
console.log(isEmtpy(() => [])
As per the lodash documentation here:
Array-like values such as arguments objects, arrays, buffers, strings, or jQuery-like collections are considered empty if they have a length of 0. Similarly, maps and sets are considered empty if they have a size of 0.
[{}].length happens to be 1. A cabbage-in-a-box, if you will. An array with one empty object. Hence, isEmpty evaluates to false. [].length, on the other hand, equals 0.
There might be a handful of other cases you want to cover, like empty array, or an array of two empty objects, etc. Variations on the following should do what you need...
let array = [{}];
// contains any empty object
console.log(_.some(array, _.isEmpty))
// contains only empty objects
console.log(_.every(array, _.isEmpty))
// contains exactly one empty object
console.log(_.every(array, _.isEmpty) && array.length == 1)<script src="https://cdnjs.cloudflare.com/ajax/libs/lodash.js/4.17.11/lodash.core.js"></script>