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The official Elementary Audio core package; this package provides the standard library for composing audio processing nodes, as well as utilities for constructing and addressing composite nodes. This package also provides a set of core algorithms shared by each available renderer that you can generally ignore.


npm install --save @elemaudio/core


import {
} from '@elemaudio/core';


A plain object through which you can access all of the available standard library nodes. For documentation on exactly which nodes are available and what they do, see the Core Library Reference.


function createNode(kind: string | Function, props: Object, children: array<NodeRepr_t | number>): NodeRepr_t;

A factory function for creating an audio node, NodeRepr_t. Every function available on el ultimately decays to a series of calls to createNode.

Typically, you'll only need to pay attention to this API for creating "Composite" nodes, which we discuss in Understanding Memoization. In that case, you'll pass a function to createNode along with a set of props and children with which your function will be invoked during the render process.

// An example composite node which composes over two series filters
function myFilterComposite({props, children}) {
return el.lowpass(
el.peak(props.cutoff / 2, 0.707, children[0])

// A helper function which feels similar to the `el.*` functions which hides away
// the explicit call to `createNode`.
function myFilter(props, input) {
return createNode(myFilter, props, input);


function isNode(a: any): bool;

A simple utility for identifying if the input argument is of type NodeRepr_t. You'll rarely need this, but it's worth noting especially for TypeScript users that some of the el.* library functions have a return type of NodeRepr_t | number, and you may find utility in isNode in those scenarios.


function resolve(n: NodeRepr_t | number): NodeRepr_t;

Very similar to the above isNode; this utility accepts an input which is either a NodeRepr_t or a number and resolves to a NodeRepr_t. Again, you'll rarely need it but perhaps for cases where the el.* library functions yield a NodeRepr_t | number type.