archives

« Bugzilla Issues Index

#2054 — 19.1.4.6 Object.prototype.toString ( ): remove "Math" and "JSON" from censored list

• bug_id: 2054
• creation_ts: 2013-10-07 01:35:00 -0700
• short_desc: 19.1.4.6 Object.prototype.toString ( ): remove "Math" and "JSON" from censored list
• delta_ts: 2013-10-29 09:46:15 -0700
• product: Draft for 6th Edition
• component: technical issue
• version: Rev 19: September 27, 2013 Draft
• rep_platform: All
• op_sys: All
• bug_status: RESOLVED
• resolution: FIXED
• priority: Normal
• bug_severity: normal
• everconfirmed: true
• reporter: André Bargull
• assigned_to: Allen Wirfs-Brock

---

• commentid: 5841
• comment_count: 0
• who: André Bargull
• bug_when: 2013-10-07 01:35:14 -0700

Math and JSON are no longer special cased in 19.1.4.6, but instead use the general @@toStringTag mechanism. But per the restriction in step 18.e `Math.toString()` currently returns `"[object ~Math]"`.



Also the NOTE isn't actually accurate anymore:
> The above definition of toString preserves the ability to use it as a reliable test
> for those specific kinds of built-in objects but it does not provide a reliable type
> testing mechanism for other kinds of built-in or program defined objects.

js> Object.defineProperty(Math, Symbol.toStringTag, {value: "NotMath"}).toString()
"[object NotMath]"

IIRC the current censoring approach is not yet set in stone, just a heads-up from me.

---

• commentid: 5862
• comment_count: 1
• who: André Bargull
• bug_when: 2013-10-07 13:10:41 -0700

(In reply to comment #0)
> Also the NOTE isn't actually accurate anymore:

Ah, manual @@toStringTag overrides are considered ok (bug 1459, comment 3), didn't remember that one when reporting this bug.

---

• commentid: 5899
• comment_count: 2
• who: Allen Wirfs-Brock
• bug_when: 2013-10-11 09:04:34 -0700

fixed in rev20 editor's draft

[[Class]] tagging for Math and JSON was added in ES5 specifically to support toString. Prior to that they were [[Class]]=="Object" I don't think any one currently can rely on the toString result for those objects.

---

• commentid: 6125
• comment_count: 3
• who: Allen Wirfs-Brock
• bug_when: 2013-10-29 09:46:15 -0700

fixed in rev20 draft, Oct. 28, 2013