What is undefined equal to?

What is undefined equal to?

It means nothing. undefined typically means a variable has been declared but not defined yet. null and undefined are falsy values. null and undefined are both primitives.

What is undefined used for?

You can use undefined and the strict equality and inequality operators to determine whether a variable has a value. In the following code, the variable x is not initialized, and the if statement evaluates to true.

Is truthy undefined?

In JavaScript, a truthy value is a value that is considered true when encountered in a Boolean context. All values are truthy unless they are defined as falsy (i.e., except for false , 0 , -0 , 0n , “” , null , undefined , and NaN ).

What does undefined mean in JavaScript?

In JavaScript, undefined means a variable has been declared but has not yet been assigned a value, such as: var testVar; alert(testVar); //shows undefined alert(typeof testVar); //shows undefined. null is an assignment value.

What is the difference between “undefined” and undefined?

As to what the difference between “undefined” and undefined is: one is a string, the other an object. typeof always returns the type of the variable as a string, because you can redefine undefined to something else so you couldn’t properly compare it anymore, but “undefined” == “undefined” is always true.

What does Undefined means?

When referring to the result of a mathematical operation, undefined means there is no meaningful result. When referring to a mathematical object which satisfies some mathematical relationship, undefined means no object satisfies that relationship.

What is the definition of undefined?

Definition of undefined. : not defined: such as. a : not clearly or precisely shown, described, or limited undefined rules undefined powers a vague, undefined feeling of dread … the true outlines of Clinton’s foreign policy remain undefined.— William Greider .

What is an example of an undefined term?

In geometry, simple words such as “point” and “line” are taken as undefined terms. In arithmetic, some arithmetic operations are called “undefined”. The most famous example is that division by zero is undefined.