javascript 函数声明后是否需要分号？
声明：本页面是StackOverFlow热门问题的中英对照翻译，遵循CC BY-SA 4.0协议，如果您需要使用它，必须同样遵循CC BY-SA许可，注明原文地址和作者信息，同时你必须将它归于原作者（不是我）：StackOverFlow
原文地址: http://stackoverflow.com/questions/11978698/
Warning: these are provided under cc-by-sa 4.0 license. You are free to use/share it, But you must attribute it to the original authors (not me):
StackOverFlow
Do we need a semicolon after function declaration?
提问by Adam Lee
Possible Duplicate:
JavaScript: When should I use a semicolon after curly braces?
Someone added semicolon after function declaration, but someone not. Is this a good practice to add semicolon after function declaration?
有人在函数声明后添加了分号，但有人没有。这是在函数声明后添加分号的好习惯吗？
function test(o) {
}
function test(o) {
};
回答by Lee
A function declarationdoes not need (and should not have) a semicolon following it:
一个函数声明不需要（也不应该）跟在它后面的分号：
function test(o) {
}
However, if you write a function as an expression, like the variable initializer below, then the statement should be terminated with a semicolon, just like any other statement would be:
但是，如果您将函数编写为表达式，就像下面的变量初始值设定项一样，那么该语句应该以分号终止，就像任何其他语句一样：
var a = function test(o) {
};
See more about constructor vs declaration(statement) vs expression.
查看更多关于构造函数、声明（语句）和表达式的信息。
回答by Norguard
What's actually happening there is you're adding an empty statement after the function.
实际发生的情况是您在函数后添加了一个空语句。
function test (o) { return o; };
could be seen as being similar to:
可以被视为类似于：
var test = 0;;
That second semicolon isn't an errorper-se. The browser treats it like a statement where absolutely nothing happened.
第二个分号本身并不是错误。浏览器将其视为绝对没有发生任何事情的声明。
There are two things to keep in mind, here.
这里有两件事要记住。
This applies ONLYto function-declarations and control-blocks (for/if/while/switch/etc).
这适用ONLY到函数声明和控制块（/ IF /同时/开关/等）。
Function-declarations should be defined at the bottom of your scope, so you don't run into problems like this:
函数声明应该在你的范围的底部定义，这样你就不会遇到这样的问题：
function test () {}
(function (window, document, undefined) { /* do stuff */ }(window, document));
Because the browser will assume that you mean function test() {}(/*return value of closure*/);Which is an error. A very bad and nasty error which is very easy to overlook.
因为浏览器会假设你的意思是function test() {}(/*return value of closure*/);哪个是错误的。一个非常糟糕和令人讨厌的错误，很容易被忽视。
But that's okay, because function-declarations can go under return statements and still work just fine.
但这没关系，因为函数声明可以在 return 语句下进行并且仍然可以正常工作。
So even if you wanted to go:
所以即使你想去：
function doStuff () {
return (function () { /*process stuff*/ test(); }());
function test () {}
}
That's going to work just peachy.
这将奏效。
回答by Kendall Frey
No.
不。
You don't need semicolons when defining a function like that.
定义这样的函数时不需要分号。
However, if you define a function like this:
但是，如果您定义这样的函数：
var test = function (o) {
}
It's not strictly necessary, but you may want to use them, especially if you put the function on one line.
这不是绝对必要的，但您可能想要使用它们，尤其是当您将该函数放在一行时。
The first way defines a function, but the second way assigns a function to a variable, and thus is a statement. Most statements are semicolon delimited. Defining functions could be considered a common counterexample, as not many people do use them.
第一种方式定义了一个函数，而第二种方式将一个函数赋值给一个变量，因此是一个语句。大多数语句都以分号分隔。定义函数可以被认为是一个常见的反例，因为没有多少人使用它们。
回答by artlung
回答by Polyov
To the browser, it doesn't matter. For matter of semantics, it only matters if you're prototyping a function or using the function statement.
对浏览器来说，没关系。对于语义问题，仅当您正在对函数进行原型设计或使用函数语句时才重要。
function stuff(stuff) {
alert(stuff);
} //don't need a semicolon
Object.prototype.stuff = function(stuff) {
alert(stuff);
}; //need a semicolon
var stuff = function(stuff) {
alert(stuff);
}; //need a semicolon
回答by Anonymous
Semicolon is not required while defining a function, but putting it on is not a mistake either.
定义函数时不需要分号，但加分号也不是错误。
One exception though, if you use function wrappers and pass the parameters, you needto add semicolons in between, example:
但是有一个例外，如果您使用函数包装器并传递参数，则需要在它们之间添加分号，例如：
(function(v){alert(v)})('1');
(function(s){alert(s)})('0')
- or it will result in error: http://jsfiddle.net/twUD3/1/
- 否则会导致错误：http: //jsfiddle.net/twUD3/1/
... Otherwise forget about them ...
... Otherwise forget about them ...
