noDuplicateParameters

JavaScript (and super languages)

Summary

Rule available since: v1.0.0
Diagnostic Category: lint/suspicious/noDuplicateParameters
This rule is recommended, which means is enabled by default.
This rule doesn’t have a fix.
The default severity of this rule is error.
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

1
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.

1
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

1
function i(i, b, c) {}
2
var j = function (j, b, c) {};
3
function k({ k, b }, { c, d }) {}
4
function l([, l]) {}
5
function foo([[a, b], [c, d]]) {}

How to configure

1
{
2
  "linter": {
3
    "rules": {
4
      "suspicious": {
5
        "noDuplicateParameters": "error"
6
      }
7
    }
8
  }
9
}