refactor: unify style of function.

Author: ulivz

lib/util/index.js

@@ -1,7 +1,7 @@
 const spawn = require('cross-spawn')
 const parseHeaders = require('./parseHeaders')
 
-exports.encodePath = function (path) {
+exports.encodePath = path => {
   return path.split('/').map(item => encodeURIComponent(item)).join('/')
 }
 
@@ -20,7 +20,7 @@ exports.normalizeHeadTag = tag => {
   }
 }
 
-exports.applyUserWebpackConfig = function (userConfig, config, isServer) {
+exports.applyUserWebpackConfig = (userConfig, config, isServer) => {
   const merge = require('webpack-merge')
   if (typeof userConfig === 'object') {
     return merge(config, userConfig)
@@ -34,7 +34,7 @@ exports.applyUserWebpackConfig = function (userConfig, config, isServer) {
   return config
 }
 
-exports.inferTitle = function (frontmatter) {
+exports.inferTitle = frontmatter => {
   if (frontmatter.data.home) {
     return 'Home'
   }