Trailing commas (sometimes called "final commas") can be useful when adding new elements, parameters, or properties to JavaScript code. If you want to add a new property, you can add a new line without modifying the previously last line if that line already uses a trailing comma. This makes version-control diffs cleaner and editing code might be less troublesome.

The JavaScript exception "WeakSet key (or WeakMap value) 'x' must be an object or an unregistered symbol" occurs when a value of invalid type is used as a key in a WeakSet or as a value in a WeakMap.

Created with the method `rmatches`.

The JavaScript strict mode-only exception "'arguments' can't be defined or assigned to in strict mode code" or "'eval' can't be defined or assigned to in strict mode code" occurs when attempting to create a binding called arguments or eval, or assign to such a name.

The JavaScript exception "is not a non-null object" occurs when an object is expected somewhere and wasn't provided. null is not an object and won't work.

The forEach() method of TypedArray instances executes a provided function once for each typed array element. This method has the same algorithm as Array.prototype.forEach().

An iterator over the contents of an instance of `BufRead` split on a particular byte.

The Object.keys() static method returns an array of a given object's own enumerable string-keyed property names.

The [Symbol.asyncDispose]() method of AsyncIterator instances implements the async disposable protocol and allows it to be disposed when used with await using. It calls and awaits the return() method of this, if it exists.

Mutable slice iterator.