Generator Extensions

Like Reactive Extensions for Generators

Installation

Add the library to your project

npm install --save generator-extensions

Activate the extensions

require('generator-extensions')

Use the synchronous extensions

function* range(a, b) {
    for (let i = a; i < b; i++) {
        yield i
    }
}

const zero = range(10,20)
    .flatMap(x => [x, -x])
    .map(x => x * 2)
    .reduce((a, b) => a + b)

Use the asynchronous extensions

async function* range(a, b) {
    for (let i = a; i < b; i++) {
        yield i
    }
}

const zero = range(10,20)
    .flatMap(x => [x, -x])
    .map(x => x * 2)
    .reduce((a, b) => a + b)

Operators

toArray

Collects the generator into a single array.

flatMap

The flatMap() method first maps each element using a mapping function, then flattens the result into a new generator.

flat

The flat([depth = 1]) flattens each element to a specified depth into a new generator.

map

The map() method creates a new generator with the results of calling a provided function on every element in the calling generator.

entries

The entries() method returns a new generator that contains the key/value pairs for each index in the generator.

filter

The filter() method creates a new generator with all elements that pass the test implemented by the provided function.

find

The find() method returns the value of the first element in the provided generator that satisfies the provided testing function.

findIndex

The findIndex() method returns the index of the first element in the generator that satisfies the provided testing function. Otherwise, it returns -1, indicating that no element passed the test.

keys

The keys() method returns a new generator that contains the keys for each index in the generator.

reduce

The reduce() method executes a reducer function (that you provide) on each element of the generator, resulting in a single output value.

some

The some() method tests whether at least one element in the generator passes the test implemented by the provided function. It returns a Boolean value.

every

The every() method tests whether all elements in the generator pass the test implemented by the provided function. It returns a Boolean value.

tap

Execute a function for each element without changing the value emitted.

count

forEach

The forEach() method executes a provided function once for each generator element.

parallel (async only)

The parallel() method executes a provided async function in parallel with other elements, up to a limit provided by the second parameter (default: Infinity). The resulting generator may be in a different order than the source generator.