A Mithril v1 route plugin for SPAs

mSPA.js

var rootProxies = [ [], [] ]

// We apply m.route to a proxy node outside of the document
// This function ensures any given root always returns the same
// proxy.
function getProxy( root ){
  var roots   = rootProxies[ 0 ]
  var proxies = rootProxies[ 1 ]
  var index   = roots.indexOf( root )
  var proxy

  if( index >= 0 ){
    proxy = proxies[ index ]
  }
  else {
    proxy = document.createElement( 'div' )

    roots.push( root )
    proxies.push( proxy )
  }

  return proxy
}

function SPA( root, fallback, endpoints, view ){
  // Unique reference for vnodes to pass between route endpoints
  // and the global view
  var vnode

  // One render function for the view, which binds the state to vnode
  function render( vnode ){
    vnode.state = {}

    return view( vnode )
  }

  // Resolves with the first route match endpoint
  new Promise( function( init ){
    // Create an onmatch function
    function matchFactory( resolver ){
      return function onmatch( routeArgs ){
        // New state object
        state = {}

        // Pass vnode-like object to the route endpoint promise
        var resolution = resolver( {
          attrs : routeArgs,
          state : state,
        } )

        // Resolve our initialisation promise if we haven't already
        resolution.then( init )

        // Pass the promise back to Mithril
        return resolution
      }
    }

    // Build a Mithril-comptabile routeMap from
    // { path : promise } key : value paires
    var routeMap = {}

    for( var path in endpoints )
      if( endpoints.hasOwnProperty( path ) )
        routeMap[ path ] = {
          onmatch : matchFactory( endpoints[ path ] )
        }

    // Attach 
    m.route( getProxy( root ), fallback, routeMap )
  } ).then( function initialise(){
    m.mount( root, view )
  } )
}