It is possible to name a variable `undefined` in a local scope, but it is a very bad idea because `undefined` is what's returned for values and properties that have not yet been created. Make `undefined` a variable and you lose your ability to test whether other variables and properties exist.

## Noncompliant Code Example

    function foo () {
       var undefined = 1; // Noncompliant
       if (nonExistantVar == undefined) { // this logic doesn't work now
         // ...
       }
     }

## Compliant Solution

    function foo () {
       var bob = 1; // anything is better than naming it 'undefined'
       if (nonExistantVar == undefined) {
         // ...
       }
     }