text: // https://github.com/berstend/puppeteer-extra/blob/c44c8bb0224c6bba2554017bfb9d7a1d0119f92f/packages/puppeteer-extra-plugin-stealth/evasions/_utils/index.js
  
  const _utils = () => {
    /**
     * A set of shared utility functions specifically for the purpose of modifying native browser APIs without leaving traces.
     *
     * Meant to be passed down in puppeteer and used in the context of the page (everything in here runs in NodeJS as well as a browser).
     *
     * Note: If for whatever reason you need to use this outside of `puppeteer-extra`:
     * Just remove the `module.exports` statement at the very bottom, the rest can be copy pasted into any browser context.
     *
     * Alternatively take a look at the `extract-stealth-evasions` package to create a finished bundle which includes these utilities.
     *
     */
    utils = {}
  
    /**
     * Wraps a JS Proxy Handler and strips it's presence from error stacks, in case the traps throw.
     *
     * The presence of a JS Proxy can be revealed as it shows up in error stack traces.
     *
     * @param {object} handler - The JS Proxy handler to wrap
     */
    utils.stripProxyFromErrors = (handler = {}) => {
      const newHandler = {}
      // We wrap each trap in the handler in a try/catch and modify the error stack if they throw
      const traps = Object.getOwnPropertyNames(handler)
      traps.forEach(trap => {
        newHandler[trap] = function () {
          try {
            // Forward the call to the defined proxy handler
            return handler[trap].apply(this, arguments || [])
          } catch (err) {
            // Stack traces differ per browser, we only support chromium based ones currently
            if (!err || !err.stack || !err.stack.includes(`at `)) {
              throw err
            }
  
            // When something throws within one of our traps the Proxy will show up in error stacks
            // An earlier implementation of this code would simply strip lines with a blacklist,
            // but it makes sense to be more surgical here and only remove lines related to our Proxy.
            // We try to use a known "anchor" line for that and strip it with everything above it.
            // If the anchor line cannot be found for some reason we fall back to our blacklist approach.
  
            const stripWithBlacklist = stack => {
              const blacklist = [
                `at Reflect.${trap} `, // e.g. Reflect.get or Reflect.apply
                `at Object.${trap} `, // e.g. Object.get or Object.apply
                `at Object.newHandler.<computed> [as ${trap}] ` // caused by this very wrapper :-)
              ]
              return (
                err.stack
                  .split('\n')
                  // Always remove the first (file) line in the stack (guaranteed to be our proxy)
                  .filter((line, index) => index !== 1)
                  // Check if the line starts with one of our blacklisted strings
                  .filter(line => !blacklist.some(bl => line.trim().startsWith(bl)))
                  .join('\n')
              )
            }
  
            const stripWithAnchor = stack => {
              const stackArr = stack.split('\n')
              const anchor = `at Object.newHandler.<computed> [as ${trap}] ` // Known first Proxy line in chromium
              const anchorIndex = stackArr.findIndex(line =>
                line.trim().startsWith(anchor)
              )
              if (anchorIndex === -1) {
                return false // 404, anchor not found
              }
              // Strip everything from the top until we reach the anchor line
              // Note: We're keeping the 1st line (zero index) as it's unrelated (e.g. `TypeError`)
              stackArr.splice(1, anchorIndex)
              return stackArr.join('\n')
            }
  
            // Try using the anchor method, fallback to blacklist if necessary
            err.stack = stripWithAnchor(err.stack) || stripWithBlacklist(err.stack)
  
            throw err // Re-throw our now sanitized error
          }
        }
      })
      return newHandler
    }
  
    /**
     * Strip error lines from stack traces until (and including) a known line the stack.
     *
     * @param {object} err - The error to sanitize
     * @param {string} anchor - The string the anchor line starts with
     */
    utils.stripErrorWithAnchor = (err, anchor) => {
      const stackArr = err.stack.split('\n')
      const anchorIndex = stackArr.findIndex(line => line.trim().startsWith(anchor))
      if (anchorIndex === -1) {
        return err // 404, anchor not found
      }
      // Strip everything from the top until we reach the anchor line (remove anchor line as well)
      // Note: We're keeping the 1st line (zero index) as it's unrelated (e.g. `TypeError`)
      stackArr.splice(1, anchorIndex)
      err.stack = stackArr.join('\n')
      return err
    }
  
    /**
     * Replace the property of an object in a stealthy way.
     *
     * Note: You also want to work on the prototype of an object most often,
     * as you'd otherwise leave traces (e.g. showing up in Object.getOwnPropertyNames(obj)).
     *
     * @see https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object/defineProperty
     *
     * @example
     * replaceProperty(WebGLRenderingContext.prototype, 'getParameter', { value: "alice" })
     * // or
     * replaceProperty(Object.getPrototypeOf(navigator), 'languages', { get: () => ['en-US', 'en'] })
     *
     * @param {object} obj - The object which has the property to replace
     * @param {string} propName - The property name to replace
     * @param {object} descriptorOverrides - e.g. { value: "alice" }
     */
    utils.replaceProperty = (obj, propName, descriptorOverrides = {}) => {
      return Object.defineProperty(obj, propName, {
        // Copy over the existing descriptors (writable, enumerable, configurable, etc)
        ...(Object.getOwnPropertyDescriptor(obj, propName) || {}),
        // Add our overrides (e.g. value, get())
        ...descriptorOverrides
      })
    }
  
    /**
     * Preload a cache of function copies and data.
     *
     * For a determined enough observer it would be possible to overwrite and sniff usage of functions
     * we use in our internal Proxies, to combat that we use a cached copy of those functions.
     *
     * This is evaluated once per execution context (e.g. window)
     */
    utils.preloadCache = () => {
      if (utils.cache) {
        return
      }
      utils.cache = {
        // Used in our proxies
        Reflect: {
          get: Reflect.get.bind(Reflect),
          apply: Reflect.apply.bind(Reflect)
        },
        // Used in `makeNativeString`
        nativeToStringStr: Function.toString + '' // => `function toString() { [native code] }`
      }
    }
  
    /**
     * Utility function to generate a cross-browser `toString` result representing native code.
     *
     * There's small differences: Chromium uses a single line, whereas FF & Webkit uses multiline strings.
     * To future-proof this we use an existing native toString result as the basis.
     *
     * The only advantage we have over the other team is that our JS runs first, hence we cache the result
     * of the native toString result once, so they cannot spoof it afterwards and reveal that we're using it.
     *
     * Note: Whenever we add a `Function.prototype.toString` proxy we should preload the cache before,
     * by executing `utils.preloadCache()` before the proxy is applied (so we don't cause recursive lookups).
     *
     * @example
     * makeNativeString('foobar') // => `function foobar() { [native code] }`
     *
     * @param {string} [name] - Optional function name
     */
    utils.makeNativeString = (name = '') => {
      // Cache (per-window) the original native toString or use that if available
      utils.preloadCache()
      return utils.cache.nativeToStringStr.replace('toString', name || '')
    }
  
    /**
     * Helper function to modify the `toString()` result of the provided object.
     *
     * Note: Use `utils.redirectToString` instead when possible.
     *
     * There's a quirk in JS Proxies that will cause the `toString()` result to differ from the vanilla Object.
     * If no string is provided we will generate a `[native code]` thing based on the name of the property object.
     *
     * @example
     * patchToString(WebGLRenderingContext.prototype.getParameter, 'function getParameter() { [native code] }')
     *
     * @param {object} obj - The object for which to modify the `toString()` representation
     * @param {string} str - Optional string used as a return value
     */
    utils.patchToString = (obj, str = '') => {
      utils.preloadCache()
  
      const toStringProxy = new Proxy(Function.prototype.toString, {
        apply: function (target, ctx) {
          // This fixes e.g. `HTMLMediaElement.prototype.canPlayType.toString + ""`
          if (ctx === Function.prototype.toString) {
            return utils.makeNativeString('toString')
          }
          // `toString` targeted at our proxied Object detected
          if (ctx === obj) {
            // We either return the optional string verbatim or derive the most desired result automatically
            return str || utils.makeNativeString(obj.name)
          }
          // Check if the toString protype of the context is the same as the global prototype,
          // if not indicates that we are doing a check across different windows., e.g. the iframeWithdirect` test case
          const hasSameProto = Object.getPrototypeOf(
            Function.prototype.toString
          ).isPrototypeOf(ctx.toString) // eslint-disable-line no-prototype-builtins
          if (!hasSameProto) {
            // Pass the call on to the local Function.prototype.toString instead
            return ctx.toString()
          }
          return target.call(ctx)
        }
      })
      utils.replaceProperty(Function.prototype, 'toString', {
        value: toStringProxy
      })
    }
  
    /**
     * Make all nested functions of an object native.
     *
     * @param {object} obj
     */
    utils.patchToStringNested = (obj = {}) => {
      return utils.execRecursively(obj, ['function'], utils.patchToString)
    }
  
    /**
     * Redirect toString requests from one object to another.
     *
     * @param {object} proxyObj - The object that toString will be called on
     * @param {object} originalObj - The object which toString result we wan to return
     */
    utils.redirectToString = (proxyObj, originalObj) => {
      utils.preloadCache()
  
      const toStringProxy = new Proxy(Function.prototype.toString, {
        apply: function (target, ctx) {
          // This fixes e.g. `HTMLMediaElement.prototype.canPlayType.toString + ""`
          if (ctx === Function.prototype.toString) {
            return utils.makeNativeString('toString')
          }
  
          // `toString` targeted at our proxied Object detected
          if (ctx === proxyObj) {
            const fallback = () =>
              originalObj && originalObj.name
                ? utils.makeNativeString(originalObj.name)
                : utils.makeNativeString(proxyObj.name)
  
            // Return the toString representation of our original object if possible
            return originalObj + '' || fallback()
          }
  
          // Check if the toString protype of the context is the same as the global prototype,
          // if not indicates that we are doing a check across different windows., e.g. the iframeWithdirect` test case
          const hasSameProto = Object.getPrototypeOf(
            Function.prototype.toString
          ).isPrototypeOf(ctx.toString) // eslint-disable-line no-prototype-builtins
          if (!hasSameProto) {
            // Pass the call on to the local Function.prototype.toString instead
            return ctx.toString()
          }
  
          return target.call(ctx)
        }
      })
      utils.replaceProperty(Function.prototype, 'toString', {
        value: toStringProxy
      })
    }
  
    /**
     * All-in-one method to replace a property with a JS Proxy using the provided Proxy handler with traps.
     *
     * Will stealthify these aspects (strip error stack traces, redirect toString, etc).
     * Note: This is meant to modify native Browser APIs and works best with prototype objects.
     *
     * @example
     * replaceWithProxy(WebGLRenderingContext.prototype, 'getParameter', proxyHandler)
     *
     * @param {object} obj - The object which has the property to replace
     * @param {string} propName - The name of the property to replace
     * @param {object} handler - The JS Proxy handler to use
     */
    utils.replaceWithProxy = (obj, propName, handler) => {
      utils.preloadCache()
      const originalObj = obj[propName]
      const proxyObj = new Proxy(obj[propName], utils.stripProxyFromErrors(handler))
  
      utils.replaceProperty(obj, propName, { value: proxyObj })
      utils.redirectToString(proxyObj, originalObj)
  
      return true
    }
  
    /**
     * All-in-one method to mock a non-existing property with a JS Proxy using the provided Proxy handler with traps.
     *
     * Will stealthify these aspects (strip error stack traces, redirect toString, etc).
     *
     * @example
     * mockWithProxy(chrome.runtime, 'sendMessage', function sendMessage() {}, proxyHandler)
     *
     * @param {object} obj - The object which has the property to replace
     * @param {string} propName - The name of the property to replace or create
     * @param {object} pseudoTarget - The JS Proxy target to use as a basis
     * @param {object} handler - The JS Proxy handler to use
     */
    utils.mockWithProxy = (obj, propName, pseudoTarget, handler) => {
      utils.preloadCache()
      const proxyObj = new Proxy(pseudoTarget, utils.stripProxyFromErrors(handler))
  
      utils.replaceProperty(obj, propName, { value: proxyObj })
      utils.patchToString(proxyObj)
  
      return true
    }
  
    /**
     * All-in-one method to create a new JS Proxy with stealth tweaks.
     *
     * This is meant to be used whenever we need a JS Proxy but don't want to replace or mock an existing known property.
     *
     * Will stealthify certain aspects of the Proxy (strip error stack traces, redirect toString, etc).
     *
     * @example
     * createProxy(navigator.mimeTypes.__proto__.namedItem, proxyHandler) // => Proxy
     *
     * @param {object} pseudoTarget - The JS Proxy target to use as a basis
     * @param {object} handler - The JS Proxy handler to use
     */
    utils.createProxy = (pseudoTarget, handler) => {
      utils.preloadCache()
      const proxyObj = new Proxy(pseudoTarget, utils.stripProxyFromErrors(handler))
      utils.patchToString(proxyObj)
  
      return proxyObj
    }
  
    /**
     * Helper function to split a full path to an Object into the first part and property.
     *
     * @example
     * splitObjPath(`HTMLMediaElement.prototype.canPlayType`)
     * // => {objName: "HTMLMediaElement.prototype", propName: "canPlayType"}
     *
     * @param {string} objPath - The full path to an object as dot notation string
     */
    utils.splitObjPath = objPath => ({
      // Remove last dot entry (property) ==> `HTMLMediaElement.prototype`
      objName: objPath
        .split('.')
        .slice(0, -1)
        .join('.'),
      // Extract last dot entry ==> `canPlayType`
      propName: objPath.split('.').slice(-1)[0]
    })
  
    /**
     * Convenience method to replace a property with a JS Proxy using the provided objPath.
     *
     * Supports a full path (dot notation) to the object as string here, in case that makes it easier.
     *
     * @example
     * replaceObjPathWithProxy('WebGLRenderingContext.prototype.getParameter', proxyHandler)
     *
     * @param {string} objPath - The full path to an object (dot notation string) to replace
     * @param {object} handler - The JS Proxy handler to use
     */
    utils.replaceObjPathWithProxy = (objPath, handler) => {
      const { objName, propName } = utils.splitObjPath(objPath)
      const obj = eval(objName) // eslint-disable-line no-eval
      return utils.replaceWithProxy(obj, propName, handler)
    }
  
    /**
     * Traverse nested properties of an object recursively and apply the given function on a whitelist of value types.
     *
     * @param {object} obj
     * @param {array} typeFilter - e.g. `['function']`
     * @param {Function} fn - e.g. `utils.patchToString`
     */
    utils.execRecursively = (obj = {}, typeFilter = [], fn) => {
      function recurse(obj) {
        for (const key in obj) {
          if (obj[key] === undefined) {
            continue
          }
          if (obj[key] && typeof obj[key] === 'object') {
            recurse(obj[key])
          } else {
            if (obj[key] && typeFilter.includes(typeof obj[key])) {
              fn.call(this, obj[key])
            }
          }
        }
      }
      recurse(obj)
      return obj
    }
  
    /**
     * Everything we run through e.g. `page.evaluate` runs in the browser context, not the NodeJS one.
     * That means we cannot just use reference variables and functions from outside code, we need to pass everything as a parameter.
     *
     * Unfortunately the data we can pass is only allowed to be of primitive types, regular functions don't survive the built-in serialization process.
     * This utility function will take an object with functions and stringify them, so we can pass them down unharmed as strings.
     *
     * We use this to pass down our utility functions as well as any other functions (to be able to split up code better).
     *
     * @see utils.materializeFns
     *
     * @param {object} fnObj - An object containing functions as properties
     */
    utils.stringifyFns = (fnObj = { hello: () => 'world' }) => {
      // Object.fromEntries() ponyfill (in 6 lines) - supported only in Node v12+, modern browsers are fine
      // https://github.com/feross/fromentries
      function fromEntries(iterable) {
        return [...iterable].reduce((obj, [key, val]) => {
          obj[key] = val
          return obj
        }, {})
      }
      return (Object.fromEntries || fromEntries)(
        Object.entries(fnObj)
          .filter(([key, value]) => typeof value === 'function')
          .map(([key, value]) => [key, value.toString()]) // eslint-disable-line no-eval
      )
    }
  
    /**
     * Utility function to reverse the process of `utils.stringifyFns`.
     * Will materialize an object with stringified functions (supports classic and fat arrow functions).
     *
     * @param {object} fnStrObj - An object containing stringified functions as properties
     */
    utils.materializeFns = (fnStrObj = { hello: "() => 'world'" }) => {
      return Object.fromEntries(
        Object.entries(fnStrObj).map(([key, value]) => {
          if (value.startsWith('function')) {
            // some trickery is needed to make oldschool functions work :-)
            return [key, eval(`() => ${value}`)()] // eslint-disable-line no-eval
          } else {
            // arrow functions just work
            return [key, eval(value)] // eslint-disable-line no-eval
          }
        })
      )
    }
  
    utils.preloadCache()
  }
  
  module.exports = _utils
  