【node-pre-gyp install --fallback-to-build 錯誤】
npm install bcrypt時遇上錯誤
此時，安裝node-gyp
npm install -g node-gyp然后，再安裝bcrypt即可。
【node-gyp】
Node.js native addon build tool
node-gyp is a cross-platform command-line tool written in Node.js for compiling native addon modules for Node.js. It bundles the gyp project used by the Chromium team and takes away the pain of dealing with the various differences in build platforms.
node-gyp用於將工具源碼編譯成ndoejs add-on
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