如何创建包含1…N的数组

我正在寻找以下方法的任何替代方法，以创建包含1到N的JavaScript数组，其中N仅在运行时已知。

var foo = [];

for (var i = 1; i <= N; i++) {
   foo.push(i);
}

对我来说，我觉得应该有一种不用循环的方法。

当前回答

“_”.重复（5）.拆分（“”）.映射（（_，i）=>i+1）将产生[1，2，3，4，5]

2019-02-14 15:48:16

其他回答

以下是摘要（在控制台中运行）：

// setup:
var n = 10000000;
function* rangeIter(a, b) {
    for (let i = a; i <= b; ++i) yield i;
}
function range(n) { 
    let a = []
    for (; n--; a[n] = n);
    return a;
}
function sequence(max, step = 1) {
    return {
        [Symbol.iterator]: function* () {
            for (let i = 1; i <= max; i += step) yield i
        }
    }
}

var t0, t1, arr;
// tests
t0 = performance.now();
arr = Array.from({ length: n }, (a, i) => 1)
t1 = performance.now();
console.log("Array.from({ length: n }, (a, i) => 1) Took " + (t1 - t0) + " milliseconds.");

t0 = performance.now();
arr = range(n);
t1 = performance.now();
console.log("range(n) Took " + (t1 - t0) + " milliseconds.");

t0 = performance.now();
arr = Array.from(rangeIter(0, n));
t1 = performance.now();
console.log("Array.from(rangeIter(0, n)) Took " + (t1 - t0) + " milliseconds.");

t0 = performance.now();
arr = [...rangeIter(0, n)];
t1 = performance.now();
console.log("[...rangeIter(0, n)] Took " + (t1 - t0) + " milliseconds.");

t0 = performance.now();
arr = Array.from(sequence(n));
t1 = performance.now();
console.log("Array.from(sequence(n)) Took " + (t1 - t0) + " milliseconds.");

t0 = performance.now();
arr = [...sequence(n)];
t1 = performance.now();
console.log("[...sequence(n)] Took " + (t1 - t0) + " milliseconds.");

t0 = performance.now();
arr = Array(n).fill(0).map(Number.call, Number);
t1 = performance.now();
console.log("Array(n).fill(0).map(Number.call, Number) Took " + (t1 - t0) + " milliseconds.");

t0 = performance.now();
arr = Array.from(Array(n).keys());
t1 = performance.now();
console.log("Array.from(Array(n).keys()) Took " + (t1 - t0) + " milliseconds.");

t0 = performance.now();
arr = [...Array(n).keys()];
t1 = performance.now();
console.log("[...Array(n).keys()] Took " + (t1 - t0) + " milliseconds.");

最快的是Array（n）.fill（0）.map（Number.call，Number），第二个是[…Array（n）.keys（）]

但是。。。rangeIter的方式非常方便（可以内联），速度快，功能更强大

2019-05-16 11:47:53

我在寻找一个功能性的解决方案，最终得到了：

function numbers(min, max) {
  return Array(max-min+2).join().split(',').map(function(e, i) { return min+i; });
}

console.log(numbers(1, 9));

注意：join（）.split（'，'）将稀疏数组转换为连续数组。

2012-06-20 21:59:06

在ES6中，您可以执行以下操作：

数组（N）.fill（）.map（（e，i）=>i+1）；

http://jsbin.com/molabiluwa/edit?js安慰

编辑：更新问题后，将数组（45）更改为数组（N）。

控制台日志(数组（45）.填充（0）.映射（（e，i）=>i+1）);

2015-12-21 03:18:10

我能产生的最少代码：

for(foo=[x=100]; x; foo[x-1]=x--);
console.log(foo);

2016-03-31 04:42:01

function arrGen(n) {
  var a = Array(n)
  while (n--) a[n] = n
  return a
}
// arrGen(10) => [0, 1, 2, 3, 4, 5, 6, 7, 8, 9]

2017-03-24 09:31:14

如何创建包含1…N的数组

推荐文章

最新文章

标签