[Medium] Swift: Using Javascript library - Swift Playground File

Swift_Playground_File.swift

import UIKit
import JavaScriptCore
import PlaygroundSupport

func generateContextJS() -> JSContext? {
    
    let context = JSContext()
    
    context?.evaluateScript("var console = { log: function(message) { _consoleLog(message) } }")
    
    let consoleLog: (String) -> Void = { message in
        print("JS Log: \(message)")
    }
    context?.setObject(consoleLog, forKeyedSubscript: "_consoleLog" as NSCopying & NSObjectProtocol)
    
    context?.exceptionHandler = { context, exception in
        print("JS Error: \(exception.debugDescription)")
    }
    
    return context
    
}

func loadJSBundle(for context: JSContext?) {
    
    guard let libraryPath = Bundle.main.path(forResource: "cson-parser-bundle", ofType: "js"),
        let libraryCode = try? String(contentsOfFile: libraryPath) else {
            return
    }
    
    context?.evaluateScript(libraryCode)
    
}

let context = generateContextJS()
loadJSBundle(for: context)

if let csonPath = Bundle.main.path(forResource: "cson-sample", ofType: "cson"), let csonData = try? String(contentsOfFile: csonPath) {
    
    context?.setObject(csonData, forKeyedSubscript: "parseStringData" as NSCopying & NSObjectProtocol)
    let jsonData = context?.evaluateScript("CSON.parse(parseStringData)")?.toDictionary()
    
    print(jsonData?.description ?? "")
    
}

PlaygroundPage.current.needsIndefiniteExecution = true