vizlearn

JavaScript Compiler

Write JavaScript and run it. Your browser's own engine in a worker thread - no install, no account, nothing sent to a server.

Updated

main.js JavaScript
Output

                

            


            

                

                    
What this is

                    
Your browser’s own JavaScript engine, running your code in a
                    worker thread. Nothing is uploaded, and the page works fully
                    offline.

                    
console.log prints objects as JSON, arrays in full,
                    and the print alias works too.

                


                

                    
What works

                    
    
                        
  • Template literals, arrow functions, destructuring,
                            async/await inside functions.
    • 
                        
  • The whole language — this is the real engine, not a
                            simulator.
    • 
                        
  • An infinite loop is stopped after 10 seconds instead of
                            freezing the tab.
    • 
                    

                


                

                    
What does not

                    
    
                        
  • document and window — there is
                            no page here, so no DOM.
    • 
                        
  • Top-level await — wrap it in an
                            async function instead.
    • 
                        
  • File system access, and input()-style prompts.
    • 
                    

                


                

                    
Looking for a language lab?

                    
The Python compiler runs real
                    CPython in the same spirit, and the
                    SQL playground backs a real SQLite
                    database.