什么时候使用分号合适？ [英] When is it appropriate to use a semicolon?

问题描述

我知道JavaScript（因此是TypeScript）在许多情况下都支持省略分号。不过，我想按照 TypeScript深入研究中的建议添加分号

I know that JavaScript (and thus TypeScript) support the omission of semicolons in many cases. Nevertheless I want to add semicolons to be unambiguous as suggested in TypeScript Deep Dive

但是我找不到列出使用分号的指南。例如，看下面的代码

However I cannot find a guide that lists where to use semicolon. For example look at the following code

class Person {
  private name: string; // A

  constructor(name: string) {
    this.name = name;
  }; // B

  public add = () => {
    return "C";
  }; // C
}; // D

我相当确定在 A 上使用分号。但是 B ， C ， D 和我的示例未涵盖的所有其他情况呢？

I'm fairly sure to use a semicolon at A. But what about B, C, D and all the other cases not covered by my example?

我不是问在哪里省略分号，而是在哪里添加它们。像 always 这样的答案不能满足我的需求，因为我不能在 public 之后添加; 。我想知道确切在哪里放置分号。

I'm not asking where to omit semicolon but where to add them. An answer like always does not fulfill my needs since I cannot add a ; after public. I want to know where exactly to put semicolon.

推荐答案

仅以 [，（或带有分号的`，并且您（几乎）是黄金**

使用与另一个答案相同的示例：

Just prefix lines starting with [, (, or ` with a semicolon and you're (almost) golden*

Using the same example as another answer:

var x = { xx : "hello", yy : "world"}
(function () {
    console.log("Hello World");
})();

我们根据以下规则添加分号：

We add a semicolon according to this rule:

var x = { xx : "hello", yy : "world"}
;(function () {

否则javascript认为我们正在尝试调用（一些函数，或 reference [一些数组。这更简单，易于理解，并且您还需要在中为循环使用分号，但是 .forEach 方法是更干净，更轻松的方法。我很自信地说这条规则涵盖了您在javascript / typescript中使用分号所需的99％的情况。

otherwise javascript thinks we're trying to call( some function, or reference[ some array. This is simpler, easier to follow, and it's visually easier to spot. You also need semicolons in for loops, but the .forEach method is a cleaner and easier method. I'd confidently say this one rule covers 99% of the scenarios you need to use a semicolon in javascript/typescript.

遵循此方法，

  return 
          7

返回后，有一个换行符，浏览器插入一个分号，终止语句，如下所示：

After return, there's a newline, and the browser inserts a semicolon, terminating the statement like this:

  return; // this will return undefined.
          7

执行以下操作：

Do this instead:

  return (
          7
  )

使用分号的Javascript实际上非常聪明，有一个开放的括号，因此在找到结束括号之前不会插入分号。

Javascript is actually pretty smart with semicolons, there's an open paren, so no semicolon is inserted until the closing paren is found.

如果您习惯放分号无处不在，并且不确切知道何时需要分号，您可以阅读长达几页的说明： http://blog.izs.me/post/2353458699/an-open-letter-to-javascript-leaders-regarding

If you have a habit of putting semicolons everywhere and not knowing exactly when they are needed, you could read this for a several page long explanation: http://blog.izs.me/post/2353458699/an-open-letter-to-javascript-leaders-regarding

我承认大多数人在每一行的末尾仍然会乱扔半冒号，但是如果您是新手并且只是学习，这是更好的方法。

I admit most people will still just litter semi colons at the end of every line, but if you're new and just learning, this is the better approach.

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