Clarification: "let" declarations are syntactically restricted and cannot appear except at the top level of a block/program

[lth]

This should not be controversial: Unlike "var", "let" cannot appear eg as the direct dependent of a control flow statement, it can only appear at the top level of an explicitly brace-delimited block or at the program's top level:

let a = 1          // legal
package {
  let b = 2        // legal
  class C {
    let c = 3      // legal
    function f() {
      let d = 4    // legal
      if (x) {
        let e = 5  // legal
      }
      if (h)
        let f = 6  // ILLEGAL!
    }
  }
}

See also #253.

(This has no impact on let-block statements and let expressions.)

[jeffdyer]

Agreed. This is uncontroversial. They are already disallowed by the ES4 grammar.

Jd

[brendan]

This is a no-brainer -- too bad JS1.7 in Firefox 2 had no brain and allowed let where ever var was allowed.

/be

[waldemar]

Agreed. This avoids hassles.

[David-Sarah Hopwood]

Proposal still relevant to ES-Harmony.