Default Param Last

Enforces default parameter(s) to be last in the function signature.

Parameters with default values are optional by nature but cannot be left out of the function call without mapping the function inputs to different parameters which is confusing and error prone. Specifying them last allows them to be left out without changing the semantics of the other parameters.

Invalid:

function f(a = 2, b) {}
function f(a = 5, b, c = 5) {}

Valid:

function f() {}
function f(a) {}
function f(a = 5) {}
function f(a, b = 5) {}
function f(a, b = 5, c = 5) {}
function f(a, b = 5, ...c) {}
function f(a = 2, b = 3) {}