Rule: Duplicate property names not allowed in object literals

title

Duplicate property names not allowed in object literals

description

Even if JavaScript allows to have duplicate property names in object literals, this is a vector for bugs as only the last instance of a duplicated property determines the actual value that will be used for it. Therefore, changing values of other occurences of a duplicated property will have no effect and may cause misunderstandings and bugs.

What's more, using duplicate property names will generate an error in JavaScript strict mode code.

The following code snippet illustrates this rule :

var data = {
  "key": "value",
  "key": "value", // Non-Compliant - duplicate of "key"
  " key": "value,
  key: "value", // Non-Compliant - duplicate of "key"
  \u006bey: "value", // Non-Compliant - duplicate of "key"
  "\u006bey": "value", // Non-Compliant - duplicate of "key"
  "\x6bey": "value", // Non-Compliant - duplicate of "key"
  "1": "value",
  1: "value" // Non-Compliant - duplicate of "1"
}

message

Rename or remove duplicate property name '

'.

severity

Critical

in Sonar way?

Yes