JavaScript: The Definitive Guide, 6th Edition

Jumps

Another category of JavaScript statements are jump statements. As the name implies, these cause the JavaScript interpreter to jump to a new location in the source code. The break statement makes the interpreter jump to the end of a loop or other statement. continue makes the interpreter skip the rest of the body of a loop and jump back to the top of a loop to begin a new iteration. JavaScript allows statements to be named, or labeled, and the break and continue can identify the target loop or other statement label.

The return statement makes the interpreter jump from a function invocation back to the code that invoked it and also supplies the value for the invocation. The throw statement raises, or “throws,” an exception and is designed to work with the try/catch/finally statement, which establishes a block of exception handling code. This is a complicated kind of jump statement: when an exception is thrown, the interpreter jumps to the nearest enclosing exception handler, which may be in the same function or up the call stack in an invoking function.

Details of each of these jump statements are in the sections that follow.

Labeled Statements

Any statement may be labeled by preceding it with an identifier and a colon:

identifier: statement

By labeling a statement, you give it a name that you can use to refer to it elsewhere in your program. You can label any statement, although it is only useful to label statements that have bodies, such as loops and conditionals. By giving a loop ...