noDuplicateParameters

Diagnostic Category: lint/suspicious/noDuplicateParameters

JavaScript (and super languages)

Since: v1.0.0

Sources:

Same as: no-dupe-args

Description

Disallow duplicate function parameter name.

If more than one parameter has the same name in a function definition, the last occurrence overrides the preceding occurrences. A duplicated name might be a typing error.

Examples

Invalid

var f = function(a, b, b) {}

code-block.js:1:24 lint/suspicious/noDuplicateParameters ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━

  ✖ Duplicate parameter name.
  
  > 1 │ var f = function(a, b, b) {}
      │                        ^
    2 │ 
  
  ℹ The parameter overrides a preceding parameter by using the same name.

function b(a, b, b) {}

code-block.js:1:18 lint/suspicious/noDuplicateParameters ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━

  ✖ Duplicate parameter name.
  
  > 1 │ function b(a, b, b) {}
      │                  ^
    2 │ 
  
  ℹ The parameter overrides a preceding parameter by using the same name.

Valid

function i(i, b, c) {}
var j = function (j, b, c) {};
function k({ k, b }, { c, d }) {}
function l([, l]) {}
function foo([[a, b], [c, d]]) {}

How to configure

{
  "linter": {
    "rules": {
      "suspicious": {
        "noDuplicateParameters": "error"
      }
    }
  }
}