问题
Just reading some of the JS tuts on Mozilla and came across the statement "You should not use an object literal at the beginning of a statement. This will lead to an error or not behave as you expect, because the { will be interpreted as the beginning of a block."
I don't understand what they mean. Could someone shed some light on this please
回答1:
An object literal starts with {
{ name: "Paul" age: 30 } // I wish
But so does a block.
{ if (age < 30) console.log ("He's lying again"); }
When the interpreter sees "{" it has to pick one interpretation (*). It picks "block" and tries to parse your object literal as if it was code. Which it isn't and so things quickly go wrong.
(*) Well, it doesn't have to, it could look ahead to see if the rest of the block looks like an object literal or code, but disambiguating the two would make the parser a lot more complicated, so the language is defined so it doesn't have to do this.
来源：https://stackoverflow.com/questions/26997647/dont-understand-why-you-should-not-use-an-object-literal-at-the-beginning-of-a