JavaScript 创建或填充任意长度数组的多种方法解析

const arr = [0,0,0];

var len = 3;
var arr = [];
for (let i=0; i < len; i++) {
  arr.push(0);
}

var len = 3;
var arr = new Array(len);

var len = 3;
var arr = new Array(len).fill(0);

var len = 3;
var obj = {};
var arr = new Array(len).fill(obj);

Array.from({length: 3})       // [ undefined, undefined, undefined ]

[...new Array(3)]             // [ undefined, undefined, undefined ]

Array.from({length: 3}, () => 0)        // [ 0, 0, 0 ]

Array.from({length: 3}, () => ({}))     // [ {}, {}, {} ]

Array.from({length: 3}, (x, i) => i)    // [ 0, 1, 2 ]

var start = 2, end = 5;
Array.from({ length: end - start }, (x, i) => i + start)    // [ 2, 3, 4 ]

[...new Array(3).keys()]              // [ 0, 1, 2 ]