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数组：reduce实现map功能 #19

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wuchaofan opened this issue Mar 19, 2018 · 0 comments

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wuchaofan commented Mar 19, 2018 •

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假设一个数组arr = [2,5,7,8]
arr.map((item)=>{ return item * 2; })
如上代码会产生一个元素都为2倍的新数组。用reduce怎么实现呢，看代码：

arr.reduce((prev, next)=>{
  return prev.push(next * 2);
}, [])

重点在于reduce的第二个参数，初始化为一个空数组。

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