Its initial value is the primitive value undefined. Typically, undefined is a variable in global scope, i.e., a property of the global object.
Undefined means that there is no value assigned to a variable – not declared. JavaScript undefined – A Straightforward Definition Void and typeof are much faster than direct comparison against undefined. Using void 0 is much easier and quicker if you know what it means – the above code is clear and concise. For instance, xyz = void 0 is slightly faster in chrome than typeof. However, the browser of choice may influence results. However, others prefer typeof because it is the safest and less error-prone method to check for undefined JavaScript values. Some users prefer xyz = undefined as it is clearer. The various techniques produce results with negligible differences. JavaScript checking for undefined is pretty straightforward regardless of the method. That explains the different techniques to check for undefined. JavaScript is constantly adding new capabilities for easy usage. – Direct Comparison of a Variable to Undefined.How to Check Undefined in JavaScript: Proven Methods.The Creation of Undefined: How Does Undefined Occur?.JavaScript undefined – A Straightforward Definition.Undefined JavaScript Value: Quick Check.The cookie is set by the GDPR Cookie Consent plugin and is used to store whether or not user has consented to the use of cookies. The cookie is used to store the user consent for the cookies in the category "Performance". This cookie is set by GDPR Cookie Consent plugin. The cookie is used to store the user consent for the cookies in the category "Other. The cookies is used to store the user consent for the cookies in the category "Necessary". The cookie is set by GDPR cookie consent to record the user consent for the cookies in the category "Functional". The cookie is used to store the user consent for the cookies in the category "Analytics". These cookies ensure basic functionalities and security features of the website, anonymously. Necessary cookies are absolutely essential for the website to function properly.
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