The Power of Undefined: Unlocking Infinite Possibilities in a Finite World

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Keyword: undefined

Keyword: undefined

The keyword undefined is a special value in JavaScript that represents the absence of a value. It is often used to indicate that a variable has not been assigned a value yet.

For example, the following code will log the value undefined to the console:

“`javascript
console.log(undefined);
“`

The undefined value is also used to indicate that an object property does not exist.

For example, the following code will log the value undefined to the console:

“`javascript
console.log(object.property);
“`

The undefined value is different from the null value. The null value is a special value that represents the intentional absence of a value. The undefined value, on the other hand, represents the absence of a value due to oversight.

How to use the undefined keyword

The undefined keyword can be used in a variety of ways.

  • To indicate that a variable has not been assigned a value yet.
  • To indicate that an object property does not exist.
  • To check if a variable is undefined.

The following code shows how to use the undefined keyword to indicate that a variable has not been assigned a value yet:

“`javascript
let variable;

console.log(variable); // undefined
“`

The following code shows how to use the undefined keyword to indicate that an object property does not exist:

“`javascript
const object = {};

console.log(object.property); // undefined
“`

The following code shows how to use the undefined keyword to check if a variable is undefined:

“`javascript
if (variable === undefined) {
// do something
}
“`

Conclusion

The undefined keyword is a useful tool for working with JavaScript. It can be used to indicate that a variable has not been assigned a value yet, to indicate that an object property does not exist, or to check if a variable is undefined.


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