这个 JS 错是为什么？

[liujianwei]

var f = function() { console.log('I am outside!'); }

(function s() {
    var f = function() { console.log('I am inside!'); }
    f();
}());

f();

"C:\Program Files\JetBrains\IntelliJ IDEA 2018.1.4\bin\runnerw.exe" C:\nodejs\node.exe C:\path\to\projects\test\src\test\test.js I am inside! C:\path\to\projects\test\src\test\test.js:8 f(); I am outside! ^

TypeError: f is not a function at Object.<anonymous> (C:\path\to\projects\test\src\test\test.js:8:1) at Module._compile (internal/modules/cjs/loader.js:689:30) at Object.Module._extensions..js (internal/modules/cjs/loader.js:700:10) at Module.load (internal/modules/cjs/loader.js:599:32) at tryModuleLoad (internal/modules/cjs/loader.js:538:12) at Function.Module._load (internal/modules/cjs/loader.js:530:3) at Function.Module.runMain (internal/modules/cjs/loader.js:742:12) at startup (internal/bootstrap/node.js:283:19) at bootstrapNodeJSCore (internal/bootstrap/node.js:743:3)</anonymous>

Process finished with exit code 1

[ccccccc]

注意分号

[yuanfnadi]

let f = function() {
console.log('I am outside!');
};
(function s() {
let f = function() {
console.log('I am inside!');
};
f();
})();

f();


请格式化代码。

[azh7138m]

https://prettier.io/playground/#N4Igxg9gdgLgprEAuEA3AhgJwAQDNsC8eArlGDAJbQAUAlNsNpFAM4QA2cAdOxAObUA5AEls6ALbYIxGCwoATOAEJBtANzYAvgB0o1XKXJUo2FnQa7sV7Bhz4iBspRr1GzNpx78hoidgqsCsqqGjom1rh0arqadOq6upHqIAA0IBAADs6syKBYmBAA7gAKWAgsyCDoqBAKqSAARpjoYADWcDAAyhktAXzIMJjEcGkAFjDi7ADqoxTwLD1gcJ3lcxSocwCelWAsFWkBLHCYMMXNfOLoyLjo7EdpAFYsAB4AQs1tHZ0ScAAyAXBrrd7iAns9On1OABFYgQeBAu4jEA9TBHTCVBroBqbXhQeoZTABGBTBQwUbIAAcAAY0gSIEcps0MpUCXA0ahAWlMHAAI7ECjcs7oC5XJA3RFpI7iCgDIZIuRQPjQ2HwsXApEwLEk+Rk5AAJjSg3QFHYfQAwhBxJdKlBoJyQMQjgAVLEVNWIzSaIA

请格式化代码+1

[no1xsyzy]

@ccccccc 可以，眼尖

[azh7138m]

@no1xsyzy 这不是眼尖吧，这是个 ASI 的问题了........

[liujianwei]

明白了！

```
var f = function() { console.log('I am outside!') }

;(function s() {
var f = function() { console.log('I am inside!') }
f()
}())

f()
```

对于不喜欢加分号的我，只要对行首字符进行判断，如果是 `[ ( + - / `五个符号之一，就在行首加分号。

[crazyrock]

@liujianwei 你这分号加开头是啥意思？

[liujianwei]

@crazyrock 就相当于加在了上一行的行位，对于解释器来说是一样的，但这样更易于，对不加分号的少数几个例外情况的规则的描述。人读着不好看的话，可以格式化一下即可。

[no1xsyzy]

@azh7138m 常见问题吗？我就是不写分号也难得碰到。
让我好好想想我是怎么个写法……

[no1xsyzy]

@crazyrock JavaScript Standard Style, available at: <https://standardjs.com/rules.html#semicolons>

[HustLiu]

这就是为什么立即执行函数括号前一般会加个分号的标准例子……

[ochatokori]

最必要加分号的地方你不加分号，还以为你是来考大家的。。。

[crazyrock]

@no1xsyzy 多谢，一直都不知道呢