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noDuplicateParameters (since v1.0.0)

Diagnostic Category: lint/suspicious/noDuplicateParameters

Sources:

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

Section titled Examples

Invalid

Section titled Invalid
var f = function(a, b, b) {}
suspicious/noDuplicateParameters.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) {}
suspicious/noDuplicateParameters.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

Section titled 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]]) {}
Section titled Related links