In Javascript, How To Determine If An Object Property Exists And Is Not Empty?

Suppose I have the next javascript object: var errors = { error_1: 'Error 1 description', error_2: 'Error 2 description', error_3: '', error_4: 'Error 4 description

Solution 1:

if (errors.hasOwnProperty('error_1') && errors['error_1'] )

The method hasOwnProperty can be used to determine whether an object has the specified property as a direct property of that object.

The errors[key] where key is a string value checks if the value exists and is not null

to Check if its not empty where it is a string then typeof errors['error_1'] === 'string' && errors['error_1'].length where you are checking for the length of a string

Result:

if (errors.hasOwnProperty('error_1') && typeof errors['error_1'] === 'string' && errors['error_1'].length)

Now, if you are using a library like underscore you can use a bunch of utility classes like _.isEmpty _.has(obj,key) and _.isString()

Solution 2:

To precisely answer your question (exists and not empty), and assuming you're not referring to empty arrays, you could use

typeof errors.error_1 === 'string' && errors.error_1.length

Solution 3:

Here is a another good answer I found and wanted to share (after modification to fit my needs):

if ("property_name" in object_name && object_name.property_name !== undefined){
   // code..
}

So if I wanted to apply this on my example, it will look like:

if ("error_1" in errors && errors.error_1 !== undefined){
   // code..
}

Solution 4:

In order to check whether the object is empty or not use this code.

if (Object.keys(object_name).length > 0) {

  // Your code

}