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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"
};
How can I determine if the property error_1 exists in the errors object and is not empty as well?
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JavaScript provides you with three common ways to check if a property exists in an object: Use the hasOwnProperty() method. Use the in operator. Compare property with undefined .
keys() method to check if there are any properties defined in an object. It returns an array of object's own keys (or property names). We can use that array to check if it's length is equal to 0 . If it is, then it means the object has no properties.
if (isEmptyObject(query)) { // There are no queries. } else { // There is at least one query, // or at least the query object is not empty. } Show activity on this post. If using underscore or jQuery, you can use their isEmpty or isEmptyObject calls.
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()
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