Hello World 对于每一个开发者来说都不生疏，因为在咱们学习任何一个语言或框架的时候，都会有一个Hello World的案例来帮忙咱们疾速入门。

如果咱们应用JavaScript来输入Hello World的话，能够这样写：

alert("Hello World");

放入HTML：

<html>  <script type="text/javascript">    alert("Hello World");  </script></html>

在浏览器中关上就能够如下状况输入Hello World了：

挑战：仅用六种字符来编写JavaScripte

下面咱们在JavaScript中实现Hello World的时候，除去HTML相干的标签和属性，下面的实现语句alert("Hello World");一共应用了13个字符，那么有没有方法用更少的字符来实现一样的性能呢？明天咱们就来挑战一下：有没有方法仅应用6个字符来编写JavaScripte程序，以实现Hello World的输入？

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先思考一下，有思路没？没思路的话，上面有提醒...

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提醒：应用这六个字符：(，)，+，[，]，!

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再思考一下，有思路没？没思路的话，上面有答案和解析...

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答案：

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什么？你不信这能够输入Hello World？那么你能够将其复制下来，放到HTML文件中，再关上试试吧！

为什么？

为什么咱们能够仅应用这6个字符来编写这些奇奇怪怪的JavaScript代码？这齐全是因为JavaScript独特的类型零碎和转换机制。

下面的6个字符能够分为三类：

  • [，]：用于创立数组
  • !，+：对数组执行一些操作
  • (，)：对操作进行分组

根底原理

  • []能够用来创立数组，而![]则能够返回false
  • 预约义的规定：2 + true，会转化为2 + 1，最初失去3
  • 预约义的规定：2 + "2"，会转化为2 + "2"，最初失去"22"

提取字母：![]能够获取false，![] + []那能够获取"false"字符串，那么咱们就能够通过下标获取其中的字母，比方：(![] + [])[1]能够获取false字符串中第二位的字母a

提取数字：![]能够获取false，因为+false能够获取0，所以+![]就能够获取到0；因为+true能够获取1，所以+!![]就能够获取到1。这样依附运算就能够获取更多其余数字

好了，有了这些根底基础知识之后，对于这个神奇的答案晓得是怎么来的了吧？

本文首发：仅用六个字符来实现Hello World，你能做到吗？，转载请注明该文章链接

参考资料

  • https://www.cnblogs.com/lzkwi...
  • http://www.jsfuck.com/
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