javascript输出返回控制台

Question

When I do a return in the console, Why does it output to the screen? I'm using chrome, but it probably does this in Firefox also. Is it assuming the console is the caller and there's a built-in function that echos the returned value?

function mike() {return "fsadf";}
mike()
"fsadf"

Answer 1

It's a feature of the console (or rather, the UI that surrounds it - sometimes there's a separate input field) that typing in a JavaScript expression will evaluate that expression and display the result. It can be very useful for debugging!

Answer 2

More generally, it echoes the value of the entered expression, for example writing 5+5 in console and pressing enter would echo 10 .

For reasoning, see http://en.wikipedia.org/wiki/Read%E2%80%93eval%E2%80%93print_loop