This sounds anticlimactic, but: "the language you already know", will almost always be the quickest way to start developing web apps.
Maybe that's not true if you're a C programmer, but pretty much any other language has a fairly good, "just what's necessary" web framework.
If you're coming from a less popular language, your options might be limited, but I can't think of any even moderately mainstream language that doesn't have at least one decent option.
If you like Java/Scala, you might look into something like Spark.
I spend considerable effort learning Python/Ruby/JavaScript (and I use JS from time to time for my work) but anyway even with the effort Java is better for me.
Comments
This sounds anticlimactic, but: "the language you already know", will almost always be the quickest way to start developing web apps.
Maybe that's not true if you're a C programmer, but pretty much any other language has a fairly good, "just what's necessary" web framework.
If you're coming from a less popular language, your options might be limited, but I can't think of any even moderately mainstream language that doesn't have at least one decent option.
If you like Java/Scala, you might look into something like Spark.
I spend considerable effort learning Python/Ruby/JavaScript (and I use JS from time to time for my work) but anyway even with the effort Java is better for me.