Remove unnecessary conditions

The code won't do anything if there are no elements, so there's no need
to check that condition.

app/assets/javascripts/imageable.js.coffee

@@ -9,8 +9,7 @@ App.Imageable =
       $("#new_image_link").removeClass("hide")
 
     $("#nested-image").on "cocoon:before-insert", ->
-      if $(".js-image-attachment").length > 0
-        $(".js-image-attachment").closest(".image").remove()
+      $(".js-image-attachment").closest(".image").remove()
 
     $("#nested-image").on "cocoon:after-insert", (e, nested_image) ->
       $("#new_image_link").addClass("hide")

app/assets/javascripts/registration_form.js.coffee

@@ -1,9 +1,7 @@
 App.RegistrationForm =
 
   initialize: ->
-
-    registrationForm = $("form#new_user[action=\"/users\"]")
-    usernameInput = $("input#user_username")
+    usernameInput = $("form#new_user[action=\"/users\"] input#user_username")
 
     clearUsernameMessage = ->
       $("small").remove()
@@ -18,8 +16,7 @@ App.RegistrationForm =
         showUsernameMessage(response)
 
 
-    if registrationForm.length > 0
-      usernameInput.on "focusout", ->
-        clearUsernameMessage()
-        username = usernameInput.val()
-        validateUsername(username) if username != ""
+    usernameInput.on "focusout", ->
+      clearUsernameMessage()
+      username = usernameInput.val()
+      validateUsername(username) if username != ""

app/assets/javascripts/tree_navigator.js.coffee

@@ -2,9 +2,6 @@ App.TreeNavigator =
   setNodes: (nodes) ->
     children = nodes.children("ul")
 
-    if(children.length == 0)
-      return
-
     children.each ->
       link = $(this).prev("a")
       $('<span class="open"></span>').insertBefore(link)
@@ -30,7 +27,6 @@ App.TreeNavigator =
           elem.siblings("ul").show()
 
     if anchor = $(location).attr("hash")
-      if link = elem.find("a[href='#{anchor}']")
-        link.parents("ul").each ->
-          $(this).show()
-          $(this).siblings("span").removeClass("closed").addClass("open")
+      elem.find("a[href='#{anchor}']").parents("ul").each ->
+        $(this).show()
+        $(this).siblings("span").removeClass("closed").addClass("open")

app/assets/javascripts/watch_form_changes.js.coffee

@@ -3,8 +3,7 @@ App.WatchFormChanges =
     return $("form[data-watch-changes]")
 
   msg: ->
-    if($("[data-watch-form-message]").length)
-      return $("[data-watch-form-message]").data("watch-form-message")
+    return $("[data-watch-form-message]").data("watch-form-message")
 
   hasChanged: ->
     App.WatchFormChanges.forms().is ->