trace step buttons now scroll 50px up or down at a time

app/assets/javascripts/build.js

@@ -27,10 +27,11 @@
       $(document).off('click', '.js-sidebar-build-toggle').on('click', '.js-sidebar-build-toggle', this.toggleSidebar);
       $(window).off('resize.build').on('resize.build', this.hideSidebar);
       $(document).off('click', '.stage-item').on('click', '.stage-item', this.updateDropdown);
+      $('.step-up-trace, .step-down-trace').off('click').on('click', this.stepTrace);
       this.updateArtifactRemoveDate();
       if ($('#build-trace').length) {
         this.getInitialBuildTrace();
-        this.initScrollButtonAffix();
+        this.initScrollButtons();
       }
       if (this.build_status === "running" || this.build_status === "pending") {
         $('#autoscroll-button').on('click', function() {
@@ -106,7 +107,7 @@
       }
     };
 
-    Build.prototype.initScrollButtonAffix = function() {
+    Build.prototype.initScrollButtons = function() {
       var $body, $buildScroll, $buildTrace;
       $buildScroll = $('#js-build-scroll');
       $body = $('body');
@@ -165,6 +166,14 @@
       this.populateJobs(stage);
     };
 
+    Build.prototype.stepTrace = function(e) {
+      if ($(e.currentTarget).hasClass('step-up-trace')) {
+          $.scrollTo('-=50px');
+      } else {
+        $.scrollTo('+=50px');
+      }
+    };
+
     return Build;
 
   })();

app/views/projects/builds/show.html.haml

@@ -34,9 +34,9 @@
         Build has been erased #{erased_by.html_safe} #{time_ago_with_tooltip(@build.erased_at)}
     - else
       #js-build-scroll.scroll-controls
-        = link_to '#build-trace', class: 'btn' do
+        %a.step-up-trace.btn
           %i.fa.fa-angle-up
-        = link_to '#down-build-trace', class: 'btn' do
+        %a.step-down-trace.btn
           %i.fa.fa-angle-down
       %pre.build-trace#build-trace
         %code.bash.js-build-output