To get all the method, use Object.getOwnPropertyNames(). This returs all properties that belong to an object.
Example
You can try to run the following code to get all methods −
Live Demo
<!DOCTYPE html> <html> <body> <script> document.write("<br>"+Object.getOwnPropertyNames(Math).filter(function (p) { return typeof Math[p] === 'function'; })); </script> </body> </html>