@cfware/history-state

Browser History API state manager.

Usage

import historyState, * as historyFunctions from '@cfware/history-state';

historyState.addEventListener('update', () => {
  /* An internal navigation has occurred with history API. */
});

historyState.addEventListener('refuse', () => {
  /* An internal navigation has been refused due to dirty state. */
  if (window.confirm('Do you really want to leave this page without saving?')) {
    /* honor the back/forward/link click requested by the user. */
    historyFunctions.bypassDirty();
  }
});

historyState.state

This should be used instead of history.state which will contain additional fields that are internal to @cfware/history-state.

Use historyState.pushState or historyState.replaceState to modify. historyState.state should be treated as if it is frozen.

Default null

historyState.pushState(state, title, url)

This must be used in place of history.pushState. This function causes an update or refuse event to be dispatched depending on historyFunctions.isDirty().

historyState.replaceState(state, title, url)

This must be used in place of history.replaceState. This replaces the current history entry.

Unlike historyState.pushState this function does not cause update or refuse to be dispatched. This function succeeds regardless of dirty status.

historyState Events

update

This is dispatched when the current location is changed, including upon window onload.

refuse

This is dispatched when a location change is refused due to historyState.dirty being true. This will happen when the user hits back/forward without leaving the SPA or when an internal link is clicked.

historyFunctions.bypassDirty()

Calling this function after a refuse event will allow navigation that was blocked by the dirty status.

historyFunctions.setDirty(value)

This can be set true or false to indicate if the current page has unsaved changes.

Default false

historyFunctions.isDirty()

Retrieve the current dirty status.

historyFunctions.linkInterceptor(element, listenerOptions)

This attaches a click event listener to element which intercepts normal clicks on any <a> element visible from element. During startup this is run for document so in most cases you will not need to run historyFunctions.linkInterceptor manually. The exception is closed shadow roots, for example:

const shadowRoot = this.attachShadow({mode: 'closed'});
this.shadowRoot.innerHTML = '<a href="/link/">link</a>';

/* The `<a>` inside shadowRoot is not visible to document because of
 * closed mode, so we have to add an interceptor directly.
 */
historyFunctions.linkInterceptor(shadowRoot);

Any link click that is intercepted results in a call to historyState.pushState.

The listenerOptions argument is passed to element.addEventListener as the second argument.

window.onbeforeunload

This component listens for beforeunload. If historyState.isDirty() is true the unload will be canceled.

links

By default this module will intercept clicks on <a> links. Links to pages within document.baseURI will be treated as part of the SPA. This is disabled per link by adding the target, download or no-history-state attributes.

The default click listener can be disabled by calling historyFunctions.setDefaultInterceptOptions(false) before window.onload occurs. Values other than false will be used as the options argument to the default interceptor.

The link interceptor will not take any action if event.preventDefault() has already been run by another listener.

window.onpopstate

This event should be ignored, monitor the update event of historyState instead.