If you’re using Proxyman, you might notice that the Scripting tool, which allows developers to write Javascript Code to easily manipulate Request/Response data.

This feature is powered by JavascriptCore framework from Apple.

The following list will write down what the Scripting can do:

• Modify the Request/Response data, include Headers, Body, Query, Encoded URL, …
• Built-in addons, such as MD5, JSON, Base64, UUID, …
• Build-in libraries, such as hashes.js, base64.js, lodash.js, crypto-js.min.js

console.log()

It’s essential to provide a function that the developer can debug their code. However, console.log() is not available in the JavascriptCore framework.

Fortunately, JavascriptCore allows us to extend a new function that can mimic the basic logic of console.log().

The following snippet code would demonstrate how to do it.

// 1. Initialize context
let context = JSContext()

// 2. Register `_console.log` function that we can capture the log
// Handy tool, so the user can use their existing JS code
let consoleLog: @convention(block) (String) -> Void = {[weak script] message in
  print(message)
}
context.setObject(consoleLog, forKeyedSubscript: "_consoleLog" as NSString)

// 3. Provide a JS Wrapper
let consoleLogFunc = """
function isObject(val) {
  if (val === null) { return false;}
  return ( (typeof val === 'function') || (typeof val === 'object') );
}

var console = { log: function(message) {
  if (isObject(message)) {
    _consoleLog(JSON.stringify(message, null, '\t'));
  } else {
    _consoleLog(message);
  }
}}
"""

// 4. done
context?.evaluateScript(consoleLogFunc)

Then, we can use it as usual.

const myObject = { name: "Proxyman" };
console.log(myObject)