仅用六个字符来完成Hello World,你能做到吗?

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Hello World 对于每一个开发者来说都不陌生,因为在我们学习任何一个语言或框架的时候,都会有一个Hello World的案例来帮助我们快速入门。

如果我们使用JavaScript来输出Hello World的话,可以这样写:

alert("Hello World");

放入HTML:

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

在浏览器中打开就可以如下情况输出Hello World了:

挑战:仅用六个字符来编写JavaScripte

上面我们在JavaScript中实现Hello World的时候,除去HTML相关的标签和属性,上面的实现语句alert("Hello World");一共使用了13个字符,那么有没有办法用更少的字符来实现一样的功能呢?今天我们就来挑战一下:有没有办法仅使用6个字符来编写JavaScripte程序,以实现Hello World的输出?



先思考一下,有思路没?没思路的话,下面有提示…







提示:使用这六个字符:()+[]!







再思考一下,有思路没?没思路的话,下面有答案和解析…







答案

<html>
<script type="text/javascript">
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</script>
</html>

什么?你不信这可以输出Hello World?那么你可以将其复制下来,放到HTML文件中,再打开试试吧!

为什么?

为什么我们可以仅使用这6个字符来编写这些奇奇怪怪的JavaScript代码?这完全是由于JavaScript独特的类型系统和转换机制。

上面的6个字符可以分为三类:

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

基础原理

  • []可以用来创建数组,而![]则可以返回false
  • 预定义的规则:2 + true,会转化为2 + 1,最后得到3
  • 预定义的规则:2 + "2",会转化为2 + "2",最后得到"22"

提取字母![]可以获取false![] + []那可以获取"false"字符串,那么我们就可以通过下标获取其中的字母,比如:(![] + [])[1]可以获取false字符串中第二位的字母a

提取数字![]可以获取false,由于+false可以获取0,所以+![]就可以获取到0;由于+true可以获取1,所以+!![]就可以获取到1。这样依靠运算就可以获取更多其他数字

好了,有了这些基础基础知识之后,对于这个神奇的答案知道是怎么来的了吧?

参考资料