What is the Difference Between null and undefined? What is the Similarity Between null and undefined? The type of variable student is also undefined. Now the student variable is having undefined value. It is also possible to set the variable value to undefined. The type of that variable is also undefined. The variable student has an undefined value. Therefore, the variable x has a value which is undefined and the type is also undefined. When writing document.write(type(x)) and reloading the page, it will still give undefined. Therefore, it contains a value of undefined. This will display the value on the HTML page. If there is a statement such as var x where x is a variable. In JavaScript, when a variable is declared but didn’t assign a value, then it is undefined. The type of x is object.Īccording to the above, the value of student is null. The document.write(x) will give the value of x. This data type is considered as an object. When the programmer wants to assign a non-value to a variable, he can use the data type null. Object properties are written as name, value pairs. JavaScript objects are written using curly braces. These objects communicate with other objects. A program or the software can be modeled into objects using JavaScript. JavaScript supports Object Oriented Programming. Side by Side Comparison – null vs undefined in JavaScript in Tabular Form Similarities Between null and undefined in JavaScriptĥ. The key difference between null and undefined in JavaScript is that null is used to assign a non-value to a variable while undefined is used when a variable is declared but not assigned with a value. This article discusses the difference between null and undefined in JavaScript. JavaScript also has composite data types that are objects etc. Numbers store numerical values, Strings store a sequence of characters and Booleans store true or false. The primitive data types are Numbers, String and Booleans. It depends on the range of values that can be stored in that memory location. A variable is a storage area that the program can manipulate. When programming with JavaScript, it is necessary to store data. JavaScript is useful to increase interactivity and to build richer interfaces. It is easy to use with HyperText Markup Language ( HTML).
JavaScript is used as a client-side scripting language to make the web pages dynamic. Key Difference – null vs undefined in JavaScript
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