为什么“{} || {}“抛出语法错误？

Question

This works:

var a = {} || {};

While this does not:

{} || {};
Uncaught SyntaxError: Unexpected token ||
    at Object.InjectedScript._evaluateOn (<anonymous>:905:140)
    at Object.InjectedScript._evaluateAndWrap (<anonymous>:838:34)
    at Object.InjectedScript.evaluate (<anonymous>:694:21)

Why is that? Tested on ff and chrome.

Answer 1

Javascript considers braces to be a code block. Try this:

({} || {});

Answer 2

Because in {} || {}; {} || {}; , the first {} is not interpreted as an [empty] object. It's interpreted as a block statement .

Try this:

({}) || {};