A reverse-iterable set implementation based on the built-in Set object
npm install reverse-iterable-setThe ReverseIterableSet object is a reverse-iterable set implementation based on the built-in Set object.
Links:
- npmjs.com/package/reverse-iterable-set
- github.com/kleinfreund/reverse-iterable-set
See also:
- ReverseIterableMap: reverse-iterable-map
- ReverseIterableArray: reverse-iterable-array
- Installation
- Usage
- Examples
- Tests
- Documentation
- Constructor
- size
- [[Symbol.toStringTag]](#symboltostringtag)
- add()
- addFirst()
- clear()
- delete()
- entries()
- forEach()
- forEachReverse()
- has()
- iteratorFor()
- reverseIterator()
- values()
- [[Symbol.iterator]()](#symboliterator)
``sh`
npm install reverse-iterable-set
`js
import ReverseIterableSet from 'reverse-iterable-set';
const set = new ReverseIterableSet();
`
For some live usage examples, clone the repository and run the following:
`sh`
npm install
npm start
Then, open localhost:8080/examples in a browser.
In order to run the tests, clone the repository and run the following:
`sh`
npm install
npm test
A ReverseIterableSet object iterates its elements in insertion or reverse-insertion order — a for...of loop returns the values for each iteration.
#### Syntax
`
new ReverseIterableSet([iterable])
Parameters:
- iterable: An iterable object.
#### Usage
`js
const set = new ReverseIterableSet([1, 2, 3]);
for (const value of set.reverseIterator()) {
console.log(value);
}
[...set.reverseIterator()]
`
The size accessor property returns the number of values in a ReverseIterableSet object.
#### Syntax
`
set.size
#### Usage
`js
const set = new ReverseIterableSet(['a', 'b', 'c']);
set.size
//> 3
`
The ReverseIterableSet[@@toStringTag] property has an initial value of “ReverseIterableSet”.
#### Syntax
`
set.add(value);
Parameters:
- value: Required. The value to add to the ReverseIterableSet object.
Return value:
- The ReverseIterableSet object.
#### Usage
`js
const set = new ReverseIterableSet();
set.add('hey');
//> ReverseIterableSet [ "hey" ]
set.add('beauty');
//> ReverseIterableSet [ "hey", "beauty" ]
set.add('hey');
//> ReverseIterableSet [ "hey", "beauty" ]
`
The add() method returns a reference to the set object. This makes the add() operation chainable.
`js`
const set = new ReverseIterableSet()
.add('key … is spelled like tea')
.add('hey … somehow ney');
//> ReverseIterableSet [ "key … is spelled like tea", "hey … somehow ney" ]
#### Syntax
`
set.clear();
Return value:
#### Usage
`js`
// Clears the underlying map object (yes, this is correct)
// Sets the first and last node references to null
set.clear();
//> undefined
#### Syntax
`
set.delete(value);
Parameters:
- value: Required. The value to remove from the ReverseIterableSet object.
Return value:
- Boolean: Returns true if the value existed in the ReverseIterableSet object and has been removed, or false if the value did not exist.
#### Usage
`js
const set = new ReverseIterableSet(['1', '2']);
set.delete('1');
//> true
set.delete('2');
//> true
set.delete('2');
//> false
`
Returns an iterator containing the [value, value] pairs for each value in the ReverseIterableSet object in insertion order.
An iterator containing the same pairs in reverse-insertion order can be obtained with entries().reverseIterator().
#### Syntax
`
set.entries();
Return value:
A new ReverseIterableSet iterator object.
#### Usage
`js
const set = new ReverseIterableSet([1, 2, 4]);
const iterator = set.entries();
iterator.next().value;
//> [1, 1]
iterator.next().value;
//> [2, 2]
iterator.next().value;
//> [4, 4]
iterator.next().value;
//> undefined
`
The forEach() method executes a provided function once for each value in the ReverseIterableSet object, in insertion order.
#### Syntax
`
set.forEach(callback[, thisArg]);
Parameters:
- callback: Function to execute for each element.
- thisArg: Value to use as this when executing callback.
Return value:
#### Usage
`js
const set = new ReverseIterableSet(['a', 'b', 'c']);
set.forEach(value => {
console.log(value);
});
//> a
//> b
//> c
set.forEach(function (value1, value2, setReference) {
console.log(value1, value2, setReference.size);
});
//> a a 3
//> b b 3
//> c c 3
`
The forEachReverse() method executes a provided function for each value in the ReverseIterableSet object, in reverse-insertion order.
#### Syntax
`
set.forEachReverse(callback[, thisArg]);
Parameters:
- callback: Function to execute for each element.
- thisArg: Value to use as this when executing callback.
Return value:
#### Usage
`js
const set = new ReverseIterableSet(['a', 'b', 'c']);
set.forEachReverse(value => {
console.log(value);
});
//> c
//> b
//> a
set.forEachReverse(function (value1, value2, setReference) {
console.log(value1, value2, setReference.size);
});
//> c c 3
//> b b 3
//> a a 3
`
#### Syntax
`
set.has(value);
Parameters:
- value: Required. The value to test for presence in the ReverseIterableSet object.
Return value:
- Boolean: Returns true if the value exists in the ReverseIterableSet object; otherwise false.
#### Usage
`js
const set = new ReverseIterableSet(['hey', 'beauty']);
set.has('hey');
//> true
set.has('beauty');
//> true
set.has('beast');
//> false
`
Returns an iterator containing the values in the ReverseIterableSet object in insertion order starting with the value specified by the value parameter.
This allows starting iteration at a specific value in the ReverseIterableSet object.
An iterator containing the same values in reverse-insertion order can be obtained with iteratorFor().reverseIterator().
#### Syntax
`
set.iteratorFor(value);
Parameters:
- value: Required. The value to start iterating from.
Return value:
A new ReverseIterableSet iterator object.
#### Usage
`js
const set = new ReverseIterableSet([1, 2, 4]);
// Iterator, starting at the element with key 1.
const iterator = set.iteratorFor(2);
iterator.next().value;
//> 2
iterator.next().value;
//> 4
iterator.next().value;
//> undefined
// Reverse-iterator, starting at the element with key 1.
const reverseIterator = set.iteratorFor(2).reverseIterator();
reverseIterator.next().value;
//> 2
reverseIterator.next().value;
//> 1
reverseIterator.next().value;
//> undefined
`
In theory, following the semantics of [Symbol.iterator](), this should be [Symbol.reverseIterator](). However, as a developer, I cannot define a well-known symbol myself and make use of it. For the time being, the reverseIterator() function serves the same purpose.
#### Syntax
`
set.reverseIterator();
Return value:
The set reverse-iterator function, which is the values().reverseIterator() function by default.
#### Usage
`js
const set = new ReverseIterableSet([1, 2, 4]);
const iterator = set.reverseIterator();
iterator.next().value;
//> 4
iterator.next().value;
//> 2
iterator.next().value;
//> 1
iterator.next().value;
//> undefined
`
Returns an iterator containing the values in the ReverseIterableSet object in insertion order.
An iterator containing the same values in reverse-insertion order can be obtained with values().reverseIterator().
#### Syntax
`
set.values();
Return value:
A new ReverseIterableSet iterator object.
#### Usage
`js
const set = new ReverseIterableSet([1, 2, 4]);
const iterator = set.values();
iterator.next().value;
//> 1
iterator.next().value;
//> 2
iterator.next().value;
//> 4
iterator.next().value;
//> undefined
`
Returns the set iterator function. By default, this is the values() function.
#### Syntax
`
set[Symbol.iterator]();
Return value:
The set iterator function, which is the values() function by default.
#### Usage
`js
const set = new ReverseIterableSet([1, 2, 4]);
const iterator = set[Symbol.iterator]();
iterator.next().value;
//> 1
iterator.next().value;
//> 2
iterator.next().value;
//> 4
iterator.next().value;
//> undefined
``