ECMAScript-regrets

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Non-intuitive if(!'property' in object)

2

`!'property' in object` is interpreted as `(!'property') in object` (=> `false in object`) which is [not what people want](https://bugzilla.mozilla.org/show_bug.cgi?id=859707#c4) the vast majority of the time. Where writing this, people want...

DavidBruant

Stateful Regexps

1

``` js re = /foo/g; alert(re.test('now foo')); alert(re.test('foo now')); This will alert first true then false #wtfjs ``` https://twitter.com/erikcorry/status/231050692553502720 https://twitter.com/BrendanEich/status/231066800304046080

DavidBruant

==

1

Arguably useless and creates more confusion than anything else.

DavidBruant

- global functions - too tolerant (should be part of a library)

DavidBruant

No need for 2 "absence representations"

14

Forked out of #25. JavaScript has both `undefined` and `null` while only one could be enough.

DavidBruant

Certain specified behaviours of native constructors can't be simulated, such as setting the `[[Class]]` and `[[PrimitiveValue]]` properties. This prevents us from constructing an instance of these constructors with a nondeterministic...

michaelficarra

Some values (like undefined) should have a reserved keywords (like null)

8

Some names (like `undefined` and `NaN`) can be used as identifiers making it hard to use them 100% reliably as values (which is what people expect naturally). This leads people...

DavidBruant

De-facto standard. Shouldn't be in the language in the first place.

DavidBruant

2 independent scripts need to communicate through some symbols, but the global object was a step too far. in ES6 let/const/import/class are staying away from the global object.

DavidBruant

behaviour of `+` operator depends on types of operands

2

`+` can mean either addition or string concatenation depending on its operands. And if neither operand is a literal (`a + b`), it becomes a chore to figure out which...

michaelficarra