有人可以解释一下 javaScript 中的“空语句”如何受到“自动分号插入”的影响

Question

Can someone explain me how the "empty statement" in javaScript is affected from "Automatic Semicolon Insertion" The MDN website states that the empty statement is affected from automatic semicolon insertion though its not stated in the ECMAScript specification can anyone explain this to me and can anyone explain me what is the difference between a semicolon and an empty statement

Answer 1

Read the spec linked from the MDN page. The empty statement is "affected" because ASI won't be done if the inserted semicolon would result in an empty statement.

Hand-wringing over when ASI happens can be dispensed with by simply including semicolons explicitly. The most common pitfall of ASI is the return statement, when attempting something like

return
  { propertyName: "something" };

Don't do that. Start the object initializer on the same line as the return .

As to the difference between a semicolon and an empty statement: a semicolon is a boundary. In the following code:

var x; ;

There's a var declaration statement, then an empty statement. The second semicolon is not part of the empty statement, but it implies that there is an empty statement before it.