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noDuplicateObjectKeys (since v1.0.0)

Diagnostic Category: lint/suspicious/noDuplicateObjectKeys

Sources:

Prevents object literals having more than one property declaration for the same name.

If an object property with the same name is defined multiple times (except when combining a getter with a setter), only the last definition makes it into the object and previous definitions are ignored, which is likely a mistake.

Examples

Section titled Examples

Invalid

Section titled Invalid
const obj = {
     a: 1,
     a: 2,
}
code-block.js:2:5 lint/suspicious/noDuplicateObjectKeys  FIXABLE  ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━

  ✖ This property value named a is later overwritten by an object member with the same name.
  
    1 │ const obj = {
  > 2 │    	a: 1,
      │    	^^^^
    3 │    	a: 2,
    4 │ }
  
  ℹ Overwritten with this value.
  
    1 │ const obj = {
    2 │    	a: 1,
  > 3 │    	a: 2,
      │    	^^^^
    4 │ }
    5 │ 
  
  ℹ If an object property with the same name is defined multiple times (except when combining a getter with a setter), only the last definition makes it into the object and previous definitions are ignored.
  
  ℹ Unsafe fix: Remove this property value named a
  
    1 1 │   const obj = {
    2   │ - ···→ a:·1,
    3 2 │      	a: 2,
    4 3 │   }
  

const obj = {
     set a(v) {},
     a: 2,
}
code-block.js:2:5 lint/suspicious/noDuplicateObjectKeys  FIXABLE  ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━

  ✖ This setter named a is later overwritten by an object member with the same name.
  
    1 │ const obj = {
  > 2 │    	set a(v) {},
      │    	^^^^^^^^^^^
    3 │    	a: 2,
    4 │ }
  
  ℹ Overwritten with this value.
  
    1 │ const obj = {
    2 │    	set a(v) {},
  > 3 │    	a: 2,
      │    	^^^^
    4 │ }
    5 │ 
  
  ℹ If an object property with the same name is defined multiple times (except when combining a getter with a setter), only the last definition makes it into the object and previous definitions are ignored.
  
  ℹ Unsafe fix: Remove this setter named a
  
    1 1 │   const obj = {
    2   │ - ···→ set·a(v)·{},
    3 2 │      	a: 2,
    4 3 │   }

Valid

Section titled Valid
const obj = {
     a: 1,
     b: 2,
}
const obj = {
     get a() { return 1; },
     set a(v) {},
}
Section titled Related links