Rule: no-null-keyword

Disallows use of the null keyword literal.

Rationale

Instead of having the dual concepts of null andundefined in a codebase, this rule ensures that only undefined is used.

JavaScript originally intended undefined to refer to a value that doesn’t yet exist, while null was meant to refer to a value that does exist but points to nothing. That’s confusing. undefined is the default value when object members don’t exist, and is the return value for newer native collection APIs such as Map.get when collection values don’t exist.

const myObject = {};
myObject.doesNotExist; // undefined

const myMap = new Map<string, number>();
myMap.get("doesNotExist"); // undefined

To remove confusion over the two similar values, it’s better to stick with just undefined.

Notes:

Config

Not configurable.

Config examples

"no-null-keyword": true

Schema

null