function keydown()

in modules/ui/preset_browser.js [208:266]
54 lines of code
22 McCabe index (conditional complexity)

    function keydown() {

        var nextFocus,
            priorFocus,
            parentSubsection;
        if (d3_event.keyCode === utilKeybinding.keyCodes['↓'] ||
            d3_event.keyCode === utilKeybinding.keyCodes.tab && !d3_event.shiftKey) {
            d3_event.preventDefault();
            d3_event.stopPropagation();

            priorFocus = poplistContent.selectAll('.list .list-item.focused');
            if (priorFocus.empty()) {
                nextFocus = poplistContent.selectAll('.list > .list-item:first-child');
            } else {
                nextFocus = d3_select(priorFocus.nodes()[0].nextElementSibling);
                if (!nextFocus.empty() && !nextFocus.classed('list-item')) {
                    nextFocus = nextFocus.selectAll('.list-item:first-child');
                }
                if (nextFocus.empty()) {
                    parentSubsection = priorFocus.nodes()[0].closest('.list .subsection');
                    if (parentSubsection && parentSubsection.nextElementSibling) {
                        nextFocus = d3_select(parentSubsection.nextElementSibling);
                    }
                }
            }
            if (!nextFocus.empty()) {
                focusListItem(nextFocus, true);
                priorFocus.classed('focused', false);
            }

        } else if (d3_event.keyCode === utilKeybinding.keyCodes['↑'] ||
            d3_event.keyCode === utilKeybinding.keyCodes.tab && d3_event.shiftKey) {
            d3_event.preventDefault();
            d3_event.stopPropagation();

            priorFocus = poplistContent.selectAll('.list .list-item.focused');
            if (!priorFocus.empty()) {

                nextFocus = d3_select(priorFocus.nodes()[0].previousElementSibling);
                if (!nextFocus.empty() && !nextFocus.classed('list-item')) {
                    nextFocus = nextFocus.selectAll('.list-item:last-child');
                }
                if (nextFocus.empty()) {
                    parentSubsection = priorFocus.nodes()[0].closest('.list .subsection');
                    if (parentSubsection && parentSubsection.previousElementSibling) {
                        nextFocus = d3_select(parentSubsection.previousElementSibling);
                    }
                }
                if (!nextFocus.empty()) {
                    focusListItem(nextFocus, true);
                    priorFocus.classed('focused', false);
                }
            }
        } else if (d3_event.keyCode === utilKeybinding.keyCodes.esc) {
            search.node().blur();
            d3_event.preventDefault();
            d3_event.stopPropagation();
        }
    }