Has JavaScript typeof ever returned "array"?

Question

I've seen this idiom show up in various open-source projects:

it instanceof Array || typeof it == "array"

I know the second half cannot be true in ECMAScript 5 (or 6), but is/was there ever an implementation that would return "array" from typeof? Or is this a case of bogus defensive programming?

Answer 1

No, at least since the first version of ECMAScript.

ECMAScript 1 (June 1997)

11.4.3 - The typeof operator

The production UnaryExpression : typeof UnaryExpression is evaluated as follows:

1. Evaluate UnaryExpression.
2. If Type(Result(1)) is Reference and GetBase(Result(1)) is null, return "undefined".
3. Call GetValue(Result(1)).

4. Return a string determined by Type(Result(3)) according to the following table:

   • Undefined: "undefined"
   • Null: "object"
   • Boolean: "boolean"
   • Number: "number"
   • String: "string"
   • Object (native and doesn’t implement [[Call]]): "object"
   • Object (native and implements [[Call]]): "function"
   • Object (host): Implementation-dependent

ECMAScript 2 (August 1998)

No changes.

ECMAScript 3 (December 1999)

No relevant changes.

11.4.3 - The typeof operator

The production UnaryExpression : typeof UnaryExpression is evaluated as follows:

1. Evaluate UnaryExpression.
2. If Type(Result(1)) is not Reference, go to step 4.
3. If GetBase(Result(1)) is null, return "undefined".
4. Call GetValue(Result(1)).

5. Return a string determined by Type(Result(4)) according to the following table:

   • Undefined: "undefined"
   • Null: "object"
   • Boolean: "boolean"
   • Number: "number"
   • String: "string"
   • Object (native and doesn’t implement [[Call]]): "object"
   • Object (native and implements [[Call]]): "function"
   • Object (host): Implementation-dependent

ECMAScript 4

This spec was abandoned.