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")()
     




posted @ 2016-01-03 17:16  陈先威  阅读(247)  评论(0)  编辑  收藏  举报