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integer list generator in JS
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// while reading "Why List Comprehension is Bad" (http://xahlee.info/comp/list_comprehension.html), | |
// I notice that JS don't have integer list generator like 0..9 or range(0,9) | |
// I wanna see if a one-liner can generate 1 list of integer i where 0 <= i < 9 | |
// ref: https://stackoverflow.com/questions/3895478/does-javascript-have-a-method-like-range-to-generate-a-range-within-the-supp | |
// benchmark: https://jsbench.me/tykijeavk9/1 (from https://stackoverflow.com/questions/3746725/how-to-create-an-array-containing-1-n/65244361#65244361) | |
// using generator | |
function*(){let i=0;while(i<9)yield i++}() | |
function*(i=0){while(i<9)yield i++}() | |
Array(9).keys() | |
[...'-'.repeat(9)].keys() | |
// using array (so it's easier to chain map, filter, ...) | |
Array(9).fill().map((v,i)=>i) | |
Array.from({length:9},(v,i)=>i) | |
Array.from(Array(9),(v,i)=>i) | |
Array.from(Array(9).keys()) | |
[...Array(9)].map((v,i)=>i) | |
[...Array(9).keys()] | |
Array(9).map((v,i)=>i) // !! Wrong, map doesn't work with sparse array | |
[...'-'.repeat(9)].map((v,i)=>i) | |
'-'.repeat(9).split('').map((v,i)=>i) | |
// using lodash :D | |
_.range(9) | |
_.range(9, 99) // 9..99 | |
_.range(0, 30, 5) // [0, 5, 10, 15, 20, 25] | |
_.range(0, -10, -1) // [0, -1, -2, -3, -4, -5, -6, -7, -8, -9] | |
// using generator on class Number (inspired by https://stackoverflow.com/questions/36947847/how-to-generate-range-of-numbers-from-0-to-n-in-es2015-only/51114450#51114450) | |
Number.prototype[Symbol.iterator]=function*(i=0){while(i<this)yield i++} | |
[...9] | |
// if we want the range 9..99 | |
Array(99 - 9).fill(9).map((v, i) => v + i) | |
Array(99 - 9).fill().map((v, i) => 9 + i) | |
Array.from(Array(99 - 9),(v, i) => 9 + i) | |
Array(99 - 9).map((v, i) => 9 + i) // !! Wrong, map doesn't work with sparse array | |
[...Array(99).keys()].slice(9) | |
[...Array(99 - 9)].map((v,i) => 9 + i) |
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