converted last method to jQuery

app/assets/javascripts/extensions/element.js.es6

+Element.prototype.matches = Element.prototype.matches || Element.prototype.msMatches;
+
+Element.prototype.closest = function closest(selector, selectedElement = this) {
+  if (!selectedElement) return;
+  return selectedElement.matches(selector) ? selectedElement : Element.prototype.closest(selector, selectedElement.parentElement);
+};

app/assets/javascripts/pipelines.js.es6

@@ -7,9 +7,9 @@
     }
 
     initGraphToggle() {
+      this.pipelineGraph = document.querySelector('.pipeline-graph');
       this.toggleButton = document.querySelector('.toggle-pipeline-btn');
       this.toggleButtonText = this.toggleButton.querySelector('.toggle-btn-text');
-      this.pipelineGraph = document.querySelector('.pipeline-graph');
       this.toggleButton.addEventListener('click', this.toggleGraph.bind(this));
     }
 
@@ -17,21 +17,22 @@
       const graphCollapsed = this.pipelineGraph.classList.contains('graph-collapsed');
       this.toggleButton.classList.toggle('graph-collapsed');
       this.pipelineGraph.classList.toggle('graph-collapsed');
-      graphCollapsed ? this.toggleButtonText.textContent = 'Hide' : this.toggleButtonText.textContent = 'Expand';
+      this.toggleButtonText.textContent = graphCollapsed ? 'Hide' : 'Expand';
     }
 
     addMarginToBuildColumns() {
-      const $secondChildBuildNode = $('.build:nth-child(2)');
-      if ($secondChildBuildNode.length) {
-        const $firstChildBuildNode = $secondChildBuildNode.prev('.build');
-        const $multiBuildColumn = $secondChildBuildNode.closest('.stage-column');
-        const $previousColumn = $multiBuildColumn.prev('.stage-column');
-        $multiBuildColumn.addClass('left-margin');
-        $firstChildBuildNode.addClass('left-connector');
-        $previousColumn.each(function() {
-          $this = $(this);
-          if ($('.build', $this).length === 1) $this.addClass('no-margin');
-        });
+      const secondChildBuildNodes = this.pipelineGraph.querySelectorAll('.build:nth-child(2)');
+      for (buildNodeIndex in secondChildBuildNodes) {
+        const buildNode = secondChildBuildNodes[buildNodeIndex];
+        const firstChildBuildNode = buildNode.previousElementSibling;
+        if (!firstChildBuildNode || !firstChildBuildNode.matches('.build')) continue;
+        const multiBuildColumn = buildNode.closest('.stage-column');
+        const previousColumn = multiBuildColumn.previousElementSibling;
+        if (!previousColumn || !previousColumn.matches('.stage-column')) continue;
+        multiBuildColumn.classList.add('left-margin');
+        firstChildBuildNode.classList.add('left-connector');
+        const columnBuilds = previousColumn.querySelectorAll('.build');
+        if (columnBuilds.length === 1) previousColumn.classList.add('no-margin');
       }
       this.pipelineGraph.classList.remove('hidden');
     }