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How to generate an arithmetic sequence using JavaScript

亚连
Release: 2018-06-23 17:48:36
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This article will share with you the use of for loops to implement js to generate simple arithmetic sequences. For specific implementation methods, please refer to this article.

The topic is very simple. The simplest way is to use for loops

let arr = []
for (let i = 0; i < b - a + 1; i++) {
 arr.push(i + a)
}
return arr
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Advanced

When I thought about it later, I felt that the previous method was a bit stupid, so I came up with these methods again

Array space

join() and toString() will treat gaps as undefined (string form):

// 拼接 > 分割 > map
Array(b - a + 1).join(&#39; &#39;).split(&#39; &#39;).map((e, i) => a + i)
// 转字符串 > 分割 > map
Array(b - a + 1).toString().split(&#39;,&#39;).map((e, i) => a + i)
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Use the Array.from method to implement:

// 空数组转真数组
Array.from(Array(b - a + 1)).map((e, i) => a + i)
// 类似数组的对象转数组
Array.from({ length: b - a + 1 }).map((e, i) => a + i)
Array.from({ length: b - a + 1 }, (e, i) => a + i)
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ES6’s expansion operator also It can help us accomplish this more conveniently

[...Array(b - a + 1)].map((e, i) => a + i)
fill()、entries()、keys()方法也不会忽略空位
Array(b - a + 1).fill(&#39; &#39;).map((e, i) => a + i)
[...Array(b - a + 1).entries()].map(e => e[0] + a)
[...Array(b - a + 1).keys()].map(e => e + a)
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There are other ways to accomplish this, such as findIndex(), find(), for...of, etc. These methods can be implemented It's not simple enough, so I won't go into details.

The above is what I compiled for everyone. I hope it will be helpful to everyone in the future.

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