安装 Bootstrap 需要各种依赖，这里面咋没写？

$ npm install bootstrap-sass --save
npm WARN ajv-keywords@3.4.1 requires a peer of ajv@^6.9.1 but none is installed. You must install peer dependencies yourself.
npm WARN sass-loader@8.0.0 requires a peer of webpack@^4.36.0 but none is installed. You must install peer dependencies yourself.
npm WARN sass-loader@8.0.0 requires a peer of node-sass@^4.0.0 but none is installed. You must install peer dependencies yourself.
npm WARN sass-loader@8.0.0 requires a peer of sass@^1.3.0 but none is installed. You must install peer dependencies yourself.
npm WARN sass-loader@8.0.0 requires a peer of fibers@>= 3.1.0 but none is installed. You must install peer dependencies yourself.
npm WARN optional SKIPPING OPTIONAL DEPENDENCY: fsevents@1.2.11 (node_modules\fsevents):
npm WARN notsup SKIPPING OPTIONAL DEPENDENCY: Unsupported platform for fsevents@1.2.11: wanted {"os":"darwin","arch":"any"} (current: {"os":"win32","arch":"x64"})

• bootstrap-sass@3.4.1
  updated 1 package in 6.758s