Popper: Fixing the rest part of wrong comments. (#2627)

.github/CONTRIBUTING.en-US.md

@@ -0,0 +1,68 @@
+# Element UI Contributing Guide
+
+First of all, it is so grateful for your usage of Element UI.
+
+Element UI is a Vue 2.0 based component library for developers, designers and product managers, with a set of design resources.
+
+When contributing to this repository, please read guides below.
+
+## Issue Guide
+
+- Issue is only used for bug, feature, and things about design, otherwise it will be closed directly. Any questions during your usage can be asked in Slack or [Gitter](https://gitter.im/ElemeFE/element).
+
+- You should search related contents before commit one new issue to reduce duplicated issues.
+
+- Please provide the versions of `Element UI` and `Vue` you are using, infos about os and browsers are required too. It is better for you to reproduce your situations in [JSFiddle](https://jsfiddle.net/).
+
+## Pull Request Guide
+
+- Please create your own fork, instead of creating branch in the repository directly.
+
+- Information about commits should format like `[Component Name]: Info about commit.` (e.g. `Button: Fix bug xxx`)
+
+- **DO NOT** commit files inside `lib`.
+
+- Make sure `npm run dist` can output the correct files.
+
+- Considering that the need of compatibility and file size, we only include `preset-2015` in `babel`. Things like `Array.prototype.find` and `Object.assign` in `ES2015` are not recommended. You can import 3rd `polyfill` if needed.
+
+- Use `reabse` before `pull request` to make sure a clean `commit`.
+
+- Make sure `pull request` to `dev` branch, instead of `master` branch.
+
+- You should write descriptions in `pull request` when fixing bugs.
+
+- Two members are required when merging codes: The first one review codes and approve the merge, then the second one review codes again and merge it.
+
+## Prerequisites
+`Node.js 4+` and `NPM 3+` are required.
+```shell
+git clone git@github.com:ElemeFE/element.git
+npm run dev
+
+# open http://localhost:8085
+```
+
+For popele in China, it is a better choice to use [yarn](https://github.com/yarnpkg/yarn) with taobao registry.
+```shell
+npm i yarn -g
+yarn config set registry https://registry.npm.taobao.org
+yarn
+npm run dev
+
+# open http://localhost:8085
+```
+
+To build:
+
+```shell
+npm run dist
+```
+
+## Component Develop Guide
+- Use `make new` to create project directory about component, which include test codes, entry file, config of cooking, documentation and `package.json`.
+- Refer to `Button` to create nested component.
+- Refer to `Select` to create component depends on other coponents.
+
+## Style Guide
+All JavaScript must adhere to  [ESLint](https://github.com/ElemeFE/eslint-config-elemefe).

.github/CONTRIBUTING.zh-CN.md

@@ -1,4 +1,4 @@
-# Element UI Contributing Guide
+# Element UI 贡献指南
 
 Hi! 首先感谢你使用 Element UI。
 

src/utils/vue-popper.js

@@ -1,5 +1,7 @@
 import Vue from 'vue';
-import { PopupManager } from 'element-ui/src/utils/popup';
+import {
+  PopupManager
+} from 'element-ui/src/utils/popup';
 
 const PopperJS = Vue.prototype.$isServer ? function() {} : require('./popper');
 const stop = e => e.stopPropagation();
@@ -7,7 +9,7 @@ const stop = e => e.stopPropagation();
 /**
  * @param {HTMLElement} [reference=$refs.reference] - The reference element used to position the popper.
  * @param {HTMLElement} [popper=$refs.popper] - The HTML element used as popper, or a configuration used to generate the popper.
- * @param {String} [placement=button] - Placement of the popper accepted values: top(-start, -end), right(-start, -end), bottom(-start, -right), left(-start, -end)
+ * @param {String} [placement=button] - Placement of the popper accepted values: top(-start, -end), right(-start, -end), bottom(-start, -end), left(-start, -end)
  * @param {Number} [offset=0] - Amount of pixels the popper will be shifted (can be negative).
  * @param {Boolean} [visible=false] Visibility of the popup element.
  * @param {Boolean} [visible-arrow=false] Visibility of the arrow, no style.
@@ -79,8 +81,8 @@ export default {
       let reference = this.referenceElm = this.referenceElm || this.reference || this.$refs.reference;
 
       if (!reference &&
-          this.$slots.reference &&
-          this.$slots.reference[0]) {
+        this.$slots.reference &&
+        this.$slots.reference[0]) {
         reference = this.referenceElm = this.$slots.reference[0].elm;
       }
       if (!popper || !reference) return;
@@ -120,12 +122,15 @@ export default {
     },
 
     resetTransformOrigin() {
-      let placementMap = { top: 'bottom', bottom: 'top', left: 'right', right: 'left' };
+      let placementMap = {
+        top: 'bottom',
+        bottom: 'top',
+        left: 'right',
+        right: 'left'
+      };
       let placement = this.popperJS._popper.getAttribute('x-placement').split('-')[0];
       let origin = placementMap[placement];
-      this.popperJS._popper.style.transformOrigin = ['top', 'bottom'].indexOf(placement) > -1
-        ? `center ${ origin }`
-        : `${ origin } center`;
+      this.popperJS._popper.style.transformOrigin = ['top', 'bottom'].indexOf(placement) > -1 ? `center ${ origin }` : `${ origin } center`;
     },
 
     appendArrow(element) {