API Reference

Quick-lookup table for TKO’s public API. Each entry links to its detailed documentation.

Observables

Function	Description
`ko.observable(value?)`	Create a reactive value. Docs
`ko.observableArray(array?)`	Observable wrapper around an array with mutation methods. Docs
`ko.isObservable(value)`	Check if a value is an observable. Docs
`ko.isObservableArray(value)`	Check if a value is an observable array. Docs
`ko.isWritableObservable(value)`	Check if a value is a writable observable. Docs
`ko.isSubscribable(value)`	Check if a value is any subscribable type. Docs
`ko.peek(value)`	Read an observable’s value without creating a dependency.
`ko.unwrap(value)`	Read an observable’s value, or return a plain value as-is. Docs
`ko.toJS(object)`	Clone an object tree, replacing observables with their values. Docs
`ko.toJSON(object, replacer?, space?)`	`ko.toJS` + `JSON.stringify`. Docs

Function	Description
`ko.computed(evaluatorOrOptions, owner?, options?)`	Create a value that depends on other observables. Accepts a function or `{ read, write }` options object. Docs
`ko.pureComputed(evaluator, owner?)`	Computed that sleeps when it has no subscribers. Docs
`ko.isComputed(value)`	Check if a value is a computed observable. Docs
`ko.isPureComputed(value)`	Check if a value is a pure computed.
`ko.ignoreDependencies(callback, owner?, args?)`	Run a function without tracking dependencies.
`ko.when(predicate, callback?, context?)`	Resolve when the predicate becomes truthy. Returns a promise, or calls callback if provided. Docs

Every observable, computed, and observable array inherits these from subscribable.fn:

Method	Description
`.subscribe(callback, target?, event?)`	Register a callback for changes. Docs
`.when(testOrValue, returnValue?)`	Promise that resolves when the test passes. Docs
`.yet(testOrValue, returnValue?)`	Promise that resolves when the test fails (negated `.when`). Docs
`.next()`	Promise that resolves on the next value change. Docs
`.once(callback)`	Call the callback on the next change, then auto-dispose. Docs
`.peek()`	Read the current value without creating a dependency.
`.dispose()`	Tear down all subscriptions.

Function	Description
`observable.extend(extenders)`	Apply extenders to an observable or computed. Docs
`rateLimit`	Throttle change notifications. Docs
`notify: 'always'`	Force notification even when value hasn’t changed. Docs

Function	Description
`ko.applyBindings(viewModel, rootNode?)`	Activate bindings on a DOM subtree. Docs
`ko.applyBindingsToNode(node, bindings, viewModelOrContext?)`	Apply bindings to a single node programmatically.
`ko.applyBindingsToDescendants(viewModelOrContext, rootNode)`	Apply bindings to descendants only (used in custom bindings). Docs
`ko.contextFor(node)`	Get the binding context for a DOM node.
`ko.dataFor(node)`	Get the view model bound to a DOM node.
`ko.cleanNode(node)`	Remove all TKO data and bindings from a node.
`ko.bindingHandlers`	Registry of built-in and custom binding handlers. Docs
`ko.bindingEvent`	Binding lifecycle event constants (e.g., `childrenComplete`, `descendantsComplete`).
`ko.BindingHandler`	Base class for class-based custom binding handlers. Docs
`ko.AsyncBindingHandler`	Async variant of `BindingHandler` for bindings that load resources. Docs

Text & HTML: text, html, textInput, value

Appearance: visible, hidden, css (alias: class), style, attr

Control flow: if, ifnot (alias: unless), else, elseif, foreach (alias: each), with, template

Context: let, using

Form: click, event (alias: on), submit, enable, disable, checked, checkedValue, options, selectedOptions, hasfocus, uniqueName

Components: component, slot

Lifecycle: descendantsComplete

Function	Description
`ko.components.register(name, config)`	Register a component. Docs
`ko.components.get(name)`	Retrieve a registered component definition. Docs
`ko.components.isRegistered(name)`	Check if a component name is registered.
`ko.components.unregister(name)`	Remove a component registration.
`ko.components.clearCachedDefinition(name)`	Clear a cached component definition.
`ko.Component`	Base class for class-based components (`ComponentABC`). Docs

Function	Description
`ko.jsx.createElement(tag, props, ...children)`	Create a JSX element. Used as the JSX factory.
`ko.jsx.Fragment`	Fragment component for grouping elements without a wrapper node.
`ko.jsx.render(jsx)`	Render JSX to DOM nodes. Returns `{ node, dispose }`.

Function	Description
`ko.domNodeDisposal.addDisposeCallback(node, callback)`	Run a callback when a DOM node is removed by TKO.
`ko.domNodeDisposal.removeDisposeCallback(node, callback)`	Remove a previously registered disposal callback.

Function	Description
`ko.subscribable.fn`	Prototype for all subscribables. Docs
`ko.observable.fn`	Prototype for all observables — add methods here. Docs
`ko.observableArray.fn`	Prototype for observable arrays (`remove`, `replace`, etc.). Docs
`ko.computed.fn`	Prototype for all computeds. Docs
`ko.tasks`	Microtask scheduler for batching async work.