Javascript is the app distribution platform that won, because the others were worse.
ActiveX? Too much lockin, no sandbox. Java applets? Too heavyweight. Flash? Nice tooling for the producer, terrible security record. ClickOnce/Silverlight? Never really got out of the gate and would have been MS/Win only.
The next generation of app distribution is "app stores" with arbitrary refusal policies which take a 30% cut of sales. A success for Apple.
Javascript mostly delivers "write once, run anywhere", albeit through a vast shifting layer of shims. Its sandbox is pretty reliable. It's not owned by anyone and they can't stop you shipping JS apps. Thus it survives.
I agree with most of what you said but you're conflating languages and platforms. JavaScript as a language says and does nothing about sandboxing. It's the browser that does that. It doesn't even specify anything about concurrency (up until promises maybe) or the event loop. The event loop is a feature of the host environment. When Netscape put JS on the server they used in CGI mode.
So I wouldn't completely remove the browser from the picture. Had it been Lua or some other simple general purpose programming language that was the language that ran in the browser I'd say it would've been the JavaScript of today.
(I think one other component of this is "worse is better". JavaScript was easy to copy and implement, although not elegant or the best designed language)
ActiveX? Too much lockin, no sandbox. Java applets? Too heavyweight. Flash? Nice tooling for the producer, terrible security record. ClickOnce/Silverlight? Never really got out of the gate and would have been MS/Win only.
The next generation of app distribution is "app stores" with arbitrary refusal policies which take a 30% cut of sales. A success for Apple.
Javascript mostly delivers "write once, run anywhere", albeit through a vast shifting layer of shims. Its sandbox is pretty reliable. It's not owned by anyone and they can't stop you shipping JS apps. Thus it survives.