vue-cli 3.x 写在public里面

(function () {
  window.API = {
    'CESHI_API_HOST': '172.168.1.1:8080'
  }
  Object.freeze(window.API)
  Object.defineProperty(window, 'API', {
    configurable: false,
    writable: false
  })
})()

vue-cli 2.x 写在static里面

都要在index.html里面引用