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undefined: Definition: A variable that has been declared but not assigned a value automatically gets the value undefined. let a; console.log(a); // undefined null: Definition: null is an intentional assignment of a non-value. It represents "nothing" or "empty." let b = null; console.log(b); // null
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undefined: Definition: A variable that has been declared but not assigned a value automatically gets the value undefined. let a; console.log(a); // undefined null: Definition: null is an intentional assignment of a non-value. It represents "nothing" or "empty." let b = null; console.log(b); // null
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Learn moreThe difference between null and undefined in JavaScript is important for writing robust code. Undefined is the default value for variables that are declared but not initialized or assigned. It is also assigned to extra parameters in a function call and to object properties that don't exist. If a function doesn't explicitly return a value, it implicitly returns undefined. Null, on the other hand, represents the intentional absence of a value. It is often used to represent no value at all. While both are falsy values, null is more explicit in checking for the absence of a value. Undefined is usually the result of default behavior in JavaScript. The next important question is the difference between null and undefined in JavaScript. Okay. So, understanding the difference between null and the undefined in JavaScript is crucial for writing robust code. Here is a breakdown of their differences. The first one is undefined. So, if you see default value, okay, variables that are declared, but not initialized or assigned to the value undefined by default. Next one is function parameters. If a function is called with fewer arguments than declared parameters, the extra parameters are assigned to the value undefined. See, for example, we have a function of parameter y. If you console the y without recalling it, that y will become undefined, okay. Next one is property not found. So, when you try to access the object, object property that does not exist, the result is undefined. Okay. Next one is return, return value. If a function does not explicitly return a value, it implicitly returns undefined, okay. So, next type is null. Okay. We have discussed so far about undefined. Now, we are going to discuss about null. Okay. So, a null is an intentional absence of value. So, null is often used to represent the intentional absence of any object value or no value at all. Next is type of, the type of null is object, which is a historical quote in JavaScript and considered a mistake. It does not mean that null is an object, it is a primitive value, okay. So, in summary, undefined is a typically a default value or the result of an uninitialized variable. While null is often used to represent the intentional absence of a value, both are falsy value, meaning they evaluate to false in a Boolean context. And checking for the absence of a value using null is more explicit, whereas undefined is often a result of the default behavior in JavaScript. So, if you have any further questions or need additional clarification, feel free to ask. Thank you for listening.
