I want to code this application idea that I have but want it to be cross-platform in the end. Is javascript html css the way to go?

By cross-platform do you mean web, mobile app and desktop?

@beningreenjam web and mobile

Maybe React.js and React Native then. I haven't really experimented with it myself yet as not had the opportunity to or need to. Although the concept seems like it'd be ideal for your purpose and great community support available.

There's this new thing called simplus.io it converts html css js into native app no webview. works on ios and android.

Kivi maybe, it's python based

That question seriously doesn't make any sense?

Meteor is a good option

Or just build the web app however the hell you usually build a web app and then write an API for the web app... which will be pretty simple if you wrote your services correctly... then simply write the mobile app to call the web services api.