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useDefaultParameterLast (since v1.0.0)

Diagnostic Category: lint/style/useDefaultParameterLast

Sources:

Enforce default function parameters and optional function parameters to be last.

Default and optional parameters that precede a required parameter cannot be omitted at call site.

Examples

Section titled Examples

Invalid

Section titled Invalid
function f(a = 0, b) {}
style/useDefaultParameterLast.js:1:12 lint/style/useDefaultParameterLast  FIXABLE  ━━━━━━━━━━━━━━━━━

  ✖ This default parameter should follow the last required parameter or should be a required parameter.
  
  > 1 │ function f(a = 0, b) {}
      │            ^^^^^
    2 │ 
  
  ℹ The last required parameter is here:
  
  > 1 │ function f(a = 0, b) {}
      │                   ^
    2 │ 
  
  ℹ A default parameter that precedes a required parameter cannot be omitted at call site.
  
  ℹ Unsafe fix: Turn the parameter into a required parameter.
  
    1 │ function·f(a·=·0,·b)·{}
      │             ----       

function f(a, b = 0, c) {}
style/useDefaultParameterLast.js:1:15 lint/style/useDefaultParameterLast  FIXABLE  ━━━━━━━━━━━━━━━━━

  ✖ This default parameter should follow the last required parameter or should be a required parameter.
  
  > 1 │ function f(a, b = 0, c) {}
      │               ^^^^^
    2 │ 
  
  ℹ The last required parameter is here:
  
  > 1 │ function f(a, b = 0, c) {}
      │                      ^
    2 │ 
  
  ℹ A default parameter that precedes a required parameter cannot be omitted at call site.
  
  ℹ Unsafe fix: Turn the parameter into a required parameter.
  
    1 │ function·f(a,·b·=·0,·c)·{}
      │                ----       

function f(a: number, b?: number, c: number) {}
style/useDefaultParameterLast.js:1:23 lint/style/useDefaultParameterLast  FIXABLE  ━━━━━━━━━━━━━━━━━

  ✖ This optional parameter should follow the last required parameter or should be a required parameter.
  
  > 1 │ function f(a: number, b?: number, c: number) {}
      │                       ^^^^^^^^^^
    2 │ 
  
  ℹ The last required parameter is here:
  
  > 1 │ function f(a: number, b?: number, c: number) {}
      │                                   ^^^^^^^^^
    2 │ 
  
  ℹ A optional parameter that precedes a required parameter cannot be omitted at call site.
  
  ℹ Unsafe fix: Turn the parameter into a required parameter.
  
    1 │ function·f(a:·number,·b?:·number,·c:·number)·{}
      │                        -                       

class Foo {
    constructor(readonly a = 10, readonly b: number) {}
}
style/useDefaultParameterLast.js:2:17 lint/style/useDefaultParameterLast  FIXABLE  ━━━━━━━━━━━━━━━━━

  ✖ This default parameter should follow the last required parameter or should be a required parameter.
  
    1 │ class Foo {
  > 2 │     constructor(readonly a = 10, readonly b: number) {}
      │                 ^^^^^^^^^^^^^^^
    3 │ }
    4 │ 
  
  ℹ The last required parameter is here:
  
    1 │ class Foo {
  > 2 │     constructor(readonly a = 10, readonly b: number) {}
      │                                  ^^^^^^^^^^^^^^^^^^
    3 │ }
    4 │ 
  
  ℹ A default parameter that precedes a required parameter cannot be omitted at call site.
  
  ℹ Unsafe fix: Turn the parameter into a required parameter.
  
    2 │ ····constructor(readonly·a·=·10,·readonly·b:·number)·{}
      │                           -----

Valid

Section titled Valid
function f(a, b = 0) {}
function f(a: number, b?: number, c = 0) {}
function f(a: number, b = 0, c?: number) {}
Section titled Related links