modern-linq

Modern-Linq

Modern-Linq is a library that brings the C# linq functionality into JavaScript. It is based on the native Iterable funtionality in JavaScript.

Examples:

const query = fromIterable([1, 2, 3, 4, 5, 6, 7])
               .where(_ => _ % 2 === 0)
               .select(_ => _ * 2);

const query = range(0, 30)
            .select(i => i * 3)
            .where(i => i > 10)
            .select(i =>
                ({
                    odd: i % 2 === 1,
                    even: i % 2 === 0,
                    num: i
                })
            )
            .skip(1)
            .take(4)
            .groupBy(i => i.odd)
            .select(_ => ({
                key: _.key,
                items: _.orderByDescending(_ => _.num).toArray()
            }))
            .orderBy(_ => _.key);

To consume the data we can use:

const arr = query.toArray();
const arr = Array.from(query); 
for (const item of query) {
    console.log(item); // Prints 4, 8, 12
}

Remarks:

1. The data is processed in the moment when is requested.
2. The sequence is immutable the output !== input

Some of the methods are using native Array implementation if the provided source is an Array Methods with native fallback:

• select: uses Array.prototype.map
• where: uses Array.prototype.filter
• take: uses Array.prototype.slice
• skip: uses Array.prototype.slice
• distinct: if no comparer is provided it uses native Set class
• count: returns Array.prototype.length
• orderBy: Array.prototype.sort
• concat: uses spread operator

Methods implemented:

• aggregate

• any

• all

• concat

• count

• distinct

• elementAt

• first

• firstOrDefault

• groupJoin

• join

• intersect

• last

• lastOrDefault

• max

• min

• ofType

• orderBy

• range

• repeat

• reverse

• select

• selectMany

• isEqual ( sequenceEqual )

• single

• skip

• skipLast

• skipWhile

• sum

• take

• takeLast

• takeWhile

• union

• where

• toArray ( toList )

• toMap ( toDictionary )

• toSet

Waiting for implementation:

• contains
• except
• zip

Extra methods

• isElementsEqual: checks if two sequences have same elements, no matter of the position.
• product: get the product of sequence.
• join (with string argument): join all elements of sequence and concat with separator
• allAndEvery: check a condition against all elements of sequence and sequence should not be empty.
• firstOrThrow: returns first element if none throw error.
• lastOrThrow: returns last element if none throw error.
• fistIndex: return index of first element which is true for a predicate
• lastIndex: return index of last element which is true for a predicate

Build status: