如何优雅地写一个「在数组中寻找指定元素」的方法 about underscore-analysis HOT 7 OPEN

@shaunzeng Since you speak Chinese, why did you comment in English in the first time?

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var isEven = function(num) {
  return !(num & 1);
};

这里面的 & 怎么理解？

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@daijinma
& 位运算与，num & 1 相当于 num % 2
关于位运算，如果有兴趣可以看下我以前写的位运算系列文章 http://www.cnblogs.com/zichi/category/732474.html

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hey, awesome article! really enjoyed learning from it!

I have a question, how is '.findIndex' not checking if it's an array or not? and how come '.sortedIndex' is not checking the obj type, but still make it work on objects?

By the way, I speak Chinese so you could response in Chinese. Really appreciate!

Thanks

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@shaunzeng
For the first question, Underscore does not do any static type checking, I think it's better to throw an error when passing a para to '.findIndex' which is not an array.

For the second, maybe '.findIndex' and '.sortedIndex' are both working on arrays? not on objects for they're both Array Functions?

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是不是因为它的二分查找并没有针对倒序的有序数组处理，因此不给予 isSorted 选项

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cb(predicate, context) 中的cb方法是如何定义的？哪里能找到

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