{}+{} incosistency
Short question - code {}+{} V8 result: "[object Object][object Object]" Safari, Firefox, Edge: NaN Which one is correct? My read of section 12.8.3.1 (tc39.github.io/ecma262/#sec-addition-operator-plus-runtime-semantics-evaluation), is that V8 is getting this right. ToPrimitive on {} will, by default, return “[object Object]” — We first call Object.prototype.valueOf(), which returns this (see 19.1.
Question about [[Enumerate]] and property decision timing
Recently, we implemented Reflect.enumerate in WebKit JSC. At that time, the question is raised "When are the enumerated keys determined?"1 For example, var object = ...; var iterator = Reflect.enumerate(object); object.newKey = "hello"; // At that time, iterator.next() is not called yet. for (var key of iterator) { print(key); // Here, "newKey" should be produced or not? } Seeing the spec, I think
revive let blocks
I'd like to ask if there's anyone on TC39 that would be willing to champion a proposal to add the let-block (let-statement) syntax? I currently write my block-scoped declarations as: { let a = 2, b, c; // .. } I do this because I want to be in the habit of always putting my let declarations at the top of blocks to avoid TDZ hazards. However, Firefox has long had the alternate let-block/statement s
ECMAScript 2015 is now an Ecma Standard
Ecma international has announced that its General Assembly has approved ECMA-262-6 The ECMAScript 2015 Language Specification as an Ecma standard www.ecma-international.org/news/index.html The official document is now available from Ecma in HTML at www.ecma-international.org/ecma-262/6.0 and as a PDF at www.ecma-international.org/ecma-262/6.0/ECMA-262.pdf I recommend that people immediately start
Actual WeakSet Use Cases
So umm... not to be annoying but I've been digging through esdiscuss and various blog posts online. I couldn't really find any use case for WeakSet (plenty of threads about naming things :P). Most material about it online fails to distinguish it from what one would use a regular Set for. All the use cases I know for WeakSet for tagging objects aren't really relevant in JS (for example - in shared
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Swift style syntax
Scoping of non-strict direct evals in ComputedPropertyNames in parameters
A new ES6 spec. draft has been posted
ES Discuss