关于node.js的模块查找顺序（require.resolve()）

时间 2019-11-11

标签关于 node.js node 模块查找顺序 require.resolve require resolve 栏目 Node.js 繁體版

原文原文链接

前几天社团群里有人问了阿里秋季前端笔试的一道题，想起来之前在官方文档看到过查找模块的算法，干脆本身写一写……html

官方的require.resolve实如今这里. 由于我只是想看看查找过程，因此就直接把会被找的路径console.log出来看看而已。代码放在了个人github gist上：https://gist.github.com/joyeec9h3/74262a250b3e880c7fd4前端

结果以下node

---------------------------------------
        check /home/somebody/node_modules/othermodule
        check /home/somebody/node_modules/othermodule.js
        check /home/somebody/node_modules/othermodule.json
        check /home/somebody/node_modules/othermodule.node
---------------------------------------
if /home/somebody/node_modules/othermodule/package.json exists
        check /home/somebody/node_modules/othermodule/package.json[main]
---------------------------------------
if /home/somebody/node_modules/othermodule/index.js exists
        check /home/somebody/node_modules/othermodule/index.js
---------------------------------------
if /home/somebody/node_modules/othermodule/index.node exists
        check /home/somebody/node_modules/othermodule/index.node
---------------------------------------
        check /home/node_modules/othermodule
        check /home/node_modules/othermodule.js
        check /home/node_modules/othermodule.json
        check /home/node_modules/othermodule.node
---------------------------------------
if /home/node_modules/othermodule/package.json exists
        check /home/node_modules/othermodule/package.json[main]
---------------------------------------
if /home/node_modules/othermodule/index.js exists
        check /home/node_modules/othermodule/index.js
---------------------------------------
if /home/node_modules/othermodule/index.node exists
        check /home/node_modules/othermodule/index.node
---------------------------------------
        check /node_modules/othermodule
        check /node_modules/othermodule.js
        check /node_modules/othermodule.json
        check /node_modules/othermodule.node
---------------------------------------
if /node_modules/othermodule/package.json exists
        check /node_modules/othermodule/package.json[main]
---------------------------------------
if /node_modules/othermodule/index.js exists
        check /node_modules/othermodule/index.js
---------------------------------------
if /node_modules/othermodule/index.node exists
        check /node_modules/othermodule/index.node
---------------------------------------

for each $PATH in $NODE_PATH

---------------------------------------
if $PATH/package.json exists
        check $PATH/package.json[main]
---------------------------------------
if $PATH/index.js exists
        check $PATH/index.js
---------------------------------------
if $PATH/index.node exists
        check $PATH/index.node
---------------------------------------
if $HOME/.node_modules/package.json exists
        check $HOME/.node_modules/package.json[main]
---------------------------------------
if $HOME/.node_modules/index.js exists
        check $HOME/.node_modules/index.js
---------------------------------------
if $HOME/.node_modules/index.node exists
        check $HOME/.node_modules/index.node
---------------------------------------
if $HOME/.node_libraries/package.json exists
        check $HOME/.node_libraries/package.json[main]
---------------------------------------
if $HOME/.node_libraries/index.js exists
        check $HOME/.node_libraries/index.js
---------------------------------------
if $HOME/.node_libraries/index.node exists
        check $HOME/.node_libraries/index.node
---------------------------------------
if $PREFIX/lib/node/package.json exists
        check $PREFIX/lib/node/package.json[main]
---------------------------------------
if $PREFIX/lib/node/index.js exists
        check $PREFIX/lib/node/index.js
---------------------------------------
if $PREFIX/lib/node/index.node exists
        check $PREFIX/lib/node/index.node

简单来讲，若是是require('x')这样开头不是相对or绝对地址符号，尾巴也没说是.js或者.json的，就当作模块来找。先找是否是core module，而后一级一级向上看node_modules文件夹，每一级的node_modules先看里面是否有basename为所找的文件，再看是否有模块名文件夹下package.json的main标明的文件，而后不死心地看看模块名文件夹下有没有index.js和index.node。最后找不到的话，还要搜一遍全局环境，好比$HOME/.node_modules/什么的。git