Method constructor

src/container.ts:84–139

(item: HTMLElement, parentWatcher?: ScrollMonitorContainer)

    eventTypes = eventTypes;

    constructor(item: HTMLElement, parentWatcher?: ScrollMonitorContainer) {
        var self = this;

        this.item = item;
        this.watchers = [];
        this.viewportTop = null;
        this.viewportBottom = null;
        this.documentHeight = getContentHeight(item);
        this.viewportHeight = getViewportHeight(item);
        this.DOMListener = function () {
            ScrollMonitorContainer.prototype.DOMListener.apply(self, arguments);
        };

        if (parentWatcher) {
            this.containerWatcher = parentWatcher.create(item);
        }

        var previousDocumentHeight: number;

        var calculateViewportI;
        function calculateViewport() {
            self.viewportTop = scrollTop(item);
            self.viewportBottom = self.viewportTop + self.viewportHeight;
            self.documentHeight = getContentHeight(item);
            if (self.documentHeight !== previousDocumentHeight) {
                calculateViewportI = self.watchers.length;
                while (calculateViewportI--) {
                    self.watchers[calculateViewportI].recalculateLocation();
                }
                previousDocumentHeight = self.documentHeight;
            }
        }

        var updateAndTriggerWatchersI;
        function updateAndTriggerWatchers() {
            // update all watchers then trigger the events so one can rely on another being up to date.
            updateAndTriggerWatchersI = self.watchers.length;
            while (updateAndTriggerWatchersI--) {
                self.watchers[updateAndTriggerWatchersI].update();
            }

            updateAndTriggerWatchersI = self.watchers.length;
            while (updateAndTriggerWatchersI--) {
                self.watchers[updateAndTriggerWatchersI].triggerCallbacks(undefined);
            }
        }

        this.update = function () {
            calculateViewport();
            updateAndTriggerWatchers();
        };
        this.recalculateLocations = function () {
            this.documentHeight = 0;
            this.update();
        };
    }

    listenToDOM() {