I18n-tasks JS AST parser call finder function

ast_call_finder.js

let fs = require('fs')
let parser = require("@babel/parser")
let traverse = require("@babel/traverse")

function collectCalls(filepath) {
  let results = []

  let code = fs.readFileSync(filepath).toString()
  let ast = parser.parse(code, {
    // parse in strict mode and allow module declarations
    sourceType: "module",

    plugins: [
      // enable jsx and flow syntax
      "jsx",
    ],
  });

  traverse.default(ast, {
    CallExpression(path) {
      //console.log(path.node)
      let { loc, start, end } = path.node
      let { type, object: objectNode, property: propertyNode } = path.node.callee

      if (type == 'MemberExpression' && objectNode.name == 'I18n' && (propertyNode.name == 't' || propertyNode.name == 'translate')) {
        let [ { value: rawKey }, defaultArg ] = path.node.arguments

        let h = {
          path: filepath,
          pos: start,
          line_num: loc.start.line,
          line_pos: loc.start.column,
          line: code.substring(start, end),
          raw_key: rawKey || null,
          default_arg: null,
        }

        if (defaultArg && defaultArg.type == 'ObjectExpression') {
          let node = defaultArg.properties.find(node => node.key.name == 'defaultValue')
          if (node) {
            if (node.value.type == 'StringLiteral') {
              h.default_arg = node.value.value
            } else if (node.value.type == 'ObjectExpression') {
              h.default_arg = node.value.properties.reduce((obj, property) => {
                obj[property.key.name] = property.value.value
                return obj
              }, {})
            }
          }
        }

        results.push(h)
      }
    },
  })
  return results
}