require 项目中 route 获取去除 component 的内容

hack-router-require.js

/* eslint-disable node/no-deprecated-api */
const fs = require('fs')

const t = require('@babel/types')
const parser = require('@babel/parser')
const generator = require('@babel/generator').default
const traverse = require('@babel/traverse').default

/**
 * 将 es6 的 routes 转为 cjs 用于 node 脚本直接使用
 * 清楚了 components 的引用
 * @param {*} targetFileRaw
 * 默认保留 字段
 */
function transformRouteJs(targetFileRaw, KEPT_PROP = ['name', 'path', 'children']) {
  const ast = parser.parse(targetFileRaw, { ast: true, sourceType: 'module' })
  const exportVars = []
  let hasDefault = false

  traverse(ast, {
    ExportNamedDeclaration(nodePath) {
      const declaration = nodePath.node.declaration
      nodePath.replaceWith(declaration)
      const varName = declaration.declarations
        .map(({ id: { start, end } }) => targetFileRaw.slice(start, end))
        .join('')
      exportVars.push(varName)
    },
    ExportDefaultDeclaration(nodePath) {
      hasDefault = true
      const declaration = nodePath.node.declaration
      // nodePath.
      nodePath.insertBefore(
        t.variableDeclaration('const', [
          t.variableDeclarator(t.identifier('__default'), declaration),
        ])
      )
      nodePath.replaceWith(
        t.expressionStatement(
          t.assignmentExpression(
            '=',
            t.memberExpression(t.identifier('module'), t.identifier('exports')),
            t.identifier('__default')
          )
        )
      )
    },
    ImportDeclaration(nodePath) {
      if (nodePath.node.source.value.startsWith('@')) {
        nodePath.remove()
        return
      }

      const specifiersRaw = nodePath.node.specifiers
        .map(({ start, end }) => {
          return targetFileRaw.slice(start, end)
        })
        .join('')
      nodePath.replaceWith(
        t.variableDeclaration('const', [
          t.variableDeclarator(
            t.identifier(specifiersRaw),
            t.callExpression(t.identifier('require'), [nodePath.node.source])
          ),
        ])
      )
    },
    Property(nodePath) {
      if (!KEPT_PROP.includes(nodePath.node.key.name)) {
        nodePath.remove()
      }
    },
  })

  return `${generator(ast).code}\
${
  exportVars.length > 0
    ? hasDefault
      ? `\
    Object.assign(__default, { ${exportVars.join(', ')} })
`
      : `\

module.exports = { ${exportVars.join(', ')} }`
    : ''
}
`
}
const defaultJsLoader = require.extensions['.js']

const hackRequire = function() {
  require.extensions['.js'] = function(module, filename) {
    const originCode = fs.readFileSync(filename).toString()
    try {
      defaultJsLoader(module, filename)
    } catch (err) {
      // console.info('尝试转换 es6', err.message)
      delete require.cache[filename]
      const transformedCode = transformRouteJs(originCode)
      module._compile(transformedCode, filename)
    }
  }
}

const restoreRequire = function() {
  require.extensions['.js'] = defaultJsLoader
}

const requireWithAutoHack = function(filename) {
  hackRequire()
  const result = require(filename)
  restoreRequire()
  return result
}

module.exports = {
  defaultJsLoader,
  transformRouteJs,
  hackRequire,
  restoreRequire,
  requireWithAutoHack,
}