瞠目结舌的JavaScript技巧

今天在知乎上看到一篇JavaScript技巧，学习并收藏之
1. 快速打印一个五分制的评分情况function getRating(rating) { if(rating > 5 || rating < 0) throw new Error('数字不在范围内'); return '★★★★★☆☆☆☆☆'.substring(5 - rating, 10 - rating );}
2.拼接重复字符串（abcabcabc）//输出n个‘abc’拼接的字符串var str = new Array(n+1).join('abc');
false => ![]
true => !![]
undefined => [][[]]
NaN => +[![]]
0 => +[]
1 => +!+[]
2 => !+[]+!+[]
10 => [+!+[]]+[+[]]
Array => []
Number => +[]
String => []+[]
Boolean => ![]
Function => []["filter"]
eval => []["filter"]["constructor"]( CODE )()
window => []["filter"]["constructor"]("return this")()
来源： <http://www.jsfuck.com/>

来自为知笔记(Wiz)