diff --git a/app/assets/javascripts/modules/sticky-element-container.js b/app/assets/javascripts/modules/sticky-element-container.js
index 0357b70ef..114011c2c 100644
--- a/app/assets/javascripts/modules/sticky-element-container.js
+++ b/app/assets/javascripts/modules/sticky-element-container.js
@@ -7,111 +7,112 @@
   Use 'data-module="sticky-element-container"' to instantiate, and add
   `[data-sticky-element]` to the child you want to position.
 */
+
+window.GOVUK = window.GOVUK || {}
+window.GOVUK.Modules = window.GOVUK.Modules || {};
+
 (function (Modules) {
-  'use strict'
+  function StickyElementContainer (element) {
+    this.wrapper = element
+    this.stickyElement = this.wrapper.querySelector('[data-sticky-element]')
+    this.hasResized = true
+    this.hasScrolled = true
+    this.interval = 50
+    this.windowVerticalPosition = 1
+    this.startPosition = 0
+    this.stopPosition = 0
+  }
+
+  StickyElementContainer.prototype.init = function () {
+    if (!this.stickyElement) return
+
+    window.onresize = this.onResize
+    window.onscroll = this.onScroll
+    setInterval(this.checkResize.bind(this), this.interval)
+    setInterval(this.checkScroll.bind(this), this.interval)
+    this.checkResize()
+    this.checkScroll()
+    this.stickyElement.classList.add('sticky-element--enabled')
+  }
+
+  StickyElementContainer.prototype.getWindowDimensions = function () {
+    return {
+      height: window.innerHeight,
+      width: window.innerWidth
+    }
+  }
+
+  StickyElementContainer.prototype.getWindowPositions = function () {
+    return {
+      scrollTop: window.scrollY
+    }
+  }
+
+  StickyElementContainer.prototype.onResize = function () {
+    this.hasResized = true
+  }
+
+  StickyElementContainer.prototype.onScroll = function () {
+    this.hasScrolled = true
+  }
 
-  Modules.StickyElementContainer = function () {
-    var self = this
+  StickyElementContainer.prototype.checkResize = function () {
+    if (this.hasResized) {
+      this.hasResized = false
+      this.hasScrolled = true
 
-    self.getWindowDimensions = function () {
-      return {
-        height: window.innerHeight,
-        width: window.innerWidth
-      }
+      var windowDimensions = this.getWindowDimensions()
+      var elementHeight = this.wrapper.offsetHeight || parseFloat(this.wrapper.style.height.replace('px', ''))
+      this.startPosition = this.wrapper.offsetTop
+      this.stopPosition = this.wrapper.offsetTop + elementHeight - windowDimensions.height
     }
+  }
+
+  StickyElementContainer.prototype.checkScroll = function () {
+    if (this.hasScrolled) {
+      this.hasScrolled = false
+      this.hasResized = true
+
+      this.windowVerticalPosition = this.getWindowPositions().scrollTop
+
+      this.updateVisibility()
+      this.updatePosition()
+    }
+  }
 
-    self.getWindowPositions = function () {
-      return {
-        scrollTop: window.scrollY
-      }
+  StickyElementContainer.prototype.updateVisibility = function () {
+    var isPastStart = this.startPosition < this.windowVerticalPosition
+    if (isPastStart) {
+      this.show()
+    } else {
+      this.hide()
     }
+  }
 
-    self.start = function ($el) {
-      var wrapper = $el[0]
-      var stickyElement = wrapper.querySelector('[data-sticky-element]')
-
-      var hasResized = true
-      var hasScrolled = true
-      var interval = 50
-      var windowVerticalPosition = 1
-      var startPosition, stopPosition
-
-      initialise()
-
-      function initialise () {
-        window.onresize = onResize
-        window.onscroll = onScroll
-        setInterval(checkResize, interval)
-        setInterval(checkScroll, interval)
-        checkResize()
-        checkScroll()
-        stickyElement.classList.add('sticky-element--enabled')
-      }
-
-      function onResize () {
-        hasResized = true
-      }
-
-      function onScroll () {
-        hasScrolled = true
-      }
-
-      function checkResize () {
-        if (hasResized) {
-          hasResized = false
-          hasScrolled = true
-
-          var windowDimensions = self.getWindowDimensions()
-          var elementHeight = wrapper.offsetHeight || parseFloat(wrapper.style.height.replace('px', ''))
-          startPosition = wrapper.offsetTop
-          stopPosition = wrapper.offsetTop + elementHeight - windowDimensions.height
-        }
-      }
-
-      function checkScroll () {
-        if (hasScrolled) {
-          hasScrolled = false
-
-          windowVerticalPosition = self.getWindowPositions().scrollTop
-
-          updateVisibility()
-          updatePosition()
-        }
-      }
-
-      function updateVisibility () {
-        var isPastStart = startPosition < windowVerticalPosition
-        if (isPastStart) {
-          show()
-        } else {
-          hide()
-        }
-      }
-
-      function updatePosition () {
-        var isPastEnd = stopPosition < windowVerticalPosition
-        if (isPastEnd) {
-          stickToParent()
-        } else {
-          stickToWindow()
-        }
-      }
-
-      function stickToWindow () {
-        stickyElement.classList.add('sticky-element--stuck-to-window')
-      }
-
-      function stickToParent () {
-        stickyElement.classList.remove('sticky-element--stuck-to-window')
-      }
-
-      function show () {
-        stickyElement.classList.remove('sticky-element--hidden')
-      }
-
-      function hide () {
-        stickyElement.classList.add('sticky-element--hidden')
-      }
+  StickyElementContainer.prototype.updatePosition = function () {
+    var isPastEnd = this.stopPosition < this.windowVerticalPosition
+    if (isPastEnd) {
+      this.stickToParent()
+    } else {
+      this.stickToWindow()
     }
   }
+
+  StickyElementContainer.prototype.stickToWindow = function () {
+    this.stickyElement.classList.add('sticky-element--stuck-to-window')
+  }
+
+  StickyElementContainer.prototype.stickToParent = function () {
+    this.stickyElement.classList.remove('sticky-element--stuck-to-window')
+  }
+
+  StickyElementContainer.prototype.show = function () {
+    this.stickyElement.classList.remove('sticky-element--hidden')
+  }
+
+  StickyElementContainer.prototype.hide = function () {
+    this.stickyElement.classList.add('sticky-element--hidden')
+  }
+
+  Modules.StickyElementContainer = StickyElementContainer
 })(window.GOVUK.Modules)
diff --git a/spec/javascripts/modules/sticky-element-container.spec.js b/spec/javascripts/modules/sticky-element-container.spec.js
index 35356892a..8c22ec286 100644
--- a/spec/javascripts/modules/sticky-element-container.spec.js
+++ b/spec/javascripts/modules/sticky-element-container.spec.js
@@ -2,62 +2,72 @@ describe('A sticky-element-container module', function () {
   'use strict'
 
   var GOVUK = window.GOVUK
-  var $ = window.$
-  var instance
 
-  beforeEach(function () {
-    instance = new GOVUK.Modules.StickyElementContainer()
-  })
+  describe('on desktop', function () {
+    var $element
+    var $footer
+    var instance
+
+    beforeEach(function () {
+      $element = $(
+        '<div data-module="sticky-element-container" style="height: 9001px; margin-bottom: 1000px">' +
+          '<div data-sticky-element>' +
+            '<span>Content</span>' +
+          '</div>' +
+        '</div>'
+      )
+
+      instance = new GOVUK.Modules.StickyElementContainer($element[0])
+      $footer = $element.find('[data-sticky-element]')
+
+      instance.getWindowDimensions = function () {
+        return {
+          height: 768,
+          width: 1024
+        }
+      }
+    })
 
-  describe('in a large parent element', function () {
-    var $element = $(
-      '<div data-module="sticky-element-container" style="height: 9001px; margin-bottom: 1000px">' +
-        '<div data-sticky-element>' +
-          '<span>Content</span>' +
-        '</div>' +
-      '</div>'
-    )
-    var $footer = $element.find('[data-sticky-element]')
-
-    describe('on desktop', function () {
-      beforeEach(function () {
-        instance.getWindowDimensions = function () {
-          return {
-            height: 768,
-            width: 1024
-          }
+    it('hides the element, when scrolled at the top', function () {
+      instance.getWindowPositions = function () {
+        return {
+          scrollTop: 0
         }
-      })
+      }
 
-      it('hides the element, when scrolled at the top', function () {
-        instance.start($element)
+      instance.checkResize()
+      instance.checkScroll()
 
-        expect($footer.hasClass('sticky-element--hidden')).toBe(true)
-      })
+      expect($footer.hasClass('sticky-element--hidden')).toBe(true)
+      expect($footer.hasClass('sticky-element--stuck-to-window')).toBe(true)
+    })
 
-      it('shows the element, stuck to the window, when scrolled in the middle', function () {
-        instance.getWindowPositions = function () {
-          return {
-            scrollTop: 5000
-          }
+    it('shows the element, stuck to the window, when scrolled in the middle', function () {
+      instance.getWindowPositions = function () {
+        return {
+          scrollTop: 5000
         }
-        instance.start($element)
+      }
 
-        expect($footer.hasClass('sticky-element--hidden')).toBe(false)
-        expect($footer.hasClass('sticky-element--stuck-to-window')).toBe(true)
-      })
+      instance.checkResize()
+      instance.checkScroll()
 
-      it('shows the element, stuck to the parent, when scrolled at the bottom', function () {
-        instance.getWindowPositions = function () {
-          return {
-            scrollTop: 9800
-          }
+      expect($footer.hasClass('sticky-element--hidden')).toBe(false)
+      expect($footer.hasClass('sticky-element--stuck-to-window')).toBe(true)
+    })
+
+    it('shows the element, stuck to the parent, when scrolled at the bottom', function () {
+      instance.getWindowPositions = function () {
+        return {
+          scrollTop: 9800
         }
-        instance.start($element)
+      }
+
+      instance.checkResize()
+      instance.checkScroll()
 
-        expect($footer.hasClass('sticky-element--hidden')).toBe(false)
-        expect($footer.hasClass('sticky-element--stuck-to-window')).toBe(false)
-      })
+      expect($footer.hasClass('sticky-element--hidden')).toBe(false)
+      expect($footer.hasClass('sticky-element--stuck-to-window')).toBe(false)
     })
   })
 })