before-build-spelled-out.js

function beforeBuild(node, cb, options) {
  // Get the last "child node" from our passed node's array of "children" inputNodes
  // (see https://github.com/broccolijs/broccoli-plugin/blob/master/index.js for
  // more context)
  var lastChildNode = node._inputNodes.pop();

  // Take that child node and wrap it with our own, new plugin. Using 
  // timmfin/broccoli-quick-plugin as a shortcut we don't have to create a new
  // contructor with all the broilerplate to extend broccoli-plugin inline.
  var wrappedChildNode = QuickPlugin([lastChildNode], {
    build: function() {
      cb();
    },
    name: "beforeBuild",
    annotation: (options || {}).annotation
  });
  
  // Next we add our wrapped child node back to the end of the "children" list
  node._inputNodes.push(wrappedChildNode);
  
  // Lastly return the modified node. When the builder builds its sorted array
  // of the whole build graph, we will now have a "hook" that is run before the 
  // build method of the original node passed to this function.
  return node;
};