循环的结果不能正常工作

Question

1. 我想遍历一个数组。
2. 任何长度大于3的索引我想缩写。
3. 我想将新缩写的月份放入新的数组中。
4. 我想通过将结果写入控制台来测试它的工作原理。

我可以让代码运行，但结果不会像我希望的那样出现。根据我的理解，循环运行，运行if语句，运行true，运行代码块。在此之后，循环应该迭代并继续，只要i＆lt; months.length，但它没有。

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var months = ["January", "Febuary", "March", "April", "May", "June", "July", "August", "September", "October", "November", "December"];
var monthsAbbrev = [];

for (var i = 0; i < months.length; i++) {
if (months[i].length > 3) {
monthsAbbrev = months[i].slice(0, 3);
}
}

console.log(monthsAbbrev);
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Answer 1

您只需使用Array.prototype.map()

即可

9

顺便说一下，你的代码中的目标数组不是pushing，这就是问题所在。

Answer 2

您需要将月份添加到monthsAbbrev数组中。一种方法是使用var months = ["January", "Febuary"]; //sample data for better understanding var monthsAbbrev = months.map(v => v.substr(0,3)); console.log(monthsAbbrev); //["Jan", "Feb"] 函数：

.push()

Answer 3

你只需要推动形成的阵列。休息你已经拥有它了。

var months = ["January", "Febuary", "March", "April", "May", "June", "July", "August", "September", "October", "November", "December"];
var monthsAbbrev = [];

for (var i = 0; i < months.length; i++) {
  if (months[i].length > 3) {
    monthsAbbrev.push(months[i].slice(0, 3));
  }
}

console.log(monthsAbbrev);

Answer 4

除了推动之外，您可以省略检查长度＆gt; 3，因为切片已经在做，并且可以防止错过某个月，例如'May'。

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var months = ["January", "Febuary", "March", "April", "May", "June", "July", "August", "September", "October", "November", "December"];
var monthsAbbrev = [];

for (var i = 0; i < months.length; i++) {
    monthsAbbrev.push(months[i].slice(0, 3));
}

console.log(monthsAbbrev);

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