進入下面任意一個倉庫下載對應操作系統的driver：
http://npm.taobao.org/mirrors/chromedriver/
http://chromedriver.storage.googleapis.com/index.html
https://chromedriver.chromium.org/downloads
解壓到home目錄下：
mkdir -p /Users/`whoami`/webdriver
cd /Users/`whoami`/webdriver
unzip ～/Downloads/chromedriver_mac64.zip
修改.bash_profile
export PATH=/Users/mac/webdriver:$PATH