The x1 attribute is used to specify the first x-coordinate for drawing an SVG element that requires more than one coordinate. Elements that only need one coordinate use the x attribute instead.

The get() method of Map instances returns a specified element from this map. If the value that is associated to the provided key is an object, then you will get a reference to that object and any change made to that object will effectively modify it inside the Map object.

The BigInt() function returns primitive values of type BigInt.

The Math.random() static method returns a floating-point, pseudo-random number that's greater than or equal to 0 and less than 1, with approximately uniform distribution over that range — which you can then scale to your desired range. The implementation selects the initial seed to the random number generation algorithm; it cannot be chosen or reset by the user.

The Math.log2() static method returns the base 2 logarithm of a number. That is

The Object.freeze() static method freezes an object. Freezing an object prevents extensions and makes existing properties non-writable and non-configurable. A frozen object can no longer be changed: new properties cannot be added, existing properties cannot be removed, their enumerability, configurability, writability, or value cannot be changed, and the object's prototype cannot be re-assigned. freeze() returns the same object that was passed in.

The forEach() method of Set instances executes a provided function once for each value in this set, in insertion order.

The register() method of FinalizationRegistry instances registers an value with this FinalizationRegistry so that if the value is garbage-collected, the registry's callback may get called.

The intersection() method of Set instances takes a set and returns a new set containing elements in both this set and the given set.

The keys() method of Map instances returns a new map iterator object that contains the keys for each element in this map in insertion order.