【javascript】一行で書かないrange関数

ワンライナー以外の記述をしたかった。

コード

const range = (from, to, step) => {
    if (Number.isFinite(from) === false) from = 0;
    if (Number.isFinite(to) === false) to = 0;
    if (Number.isFinite(step) === false || step < 1) step = 1;

    if (from === to) return [to];

    const result = new Array();
    if (from < to) {
        for (; from <= to; from += step) result.push(from);
    } else {
        for (; from >= to; from -= step) result.push(from);
    }
    return result;
};

console.log( range() );             //[0]
console.log( range(5, 5) );         //[5]

console.log( range(-5) );           //[-5, -4, -3, -2, -1, 0]
console.log( range(5) );            //[5, 4, 3, 2, 1, 0]

console.log( range(-5, 5) );        //[-5, -4, -3, -2, -1, 0, 1, 2, 3, 4, 5]
console.log( range(5, -5) );        //[5, 4, 3, 2, 1, 0, -1, -2, -3, -4, -5]

console.log( range(-5, 5, 2) );     //[-5, -3, -1, 1, 3, 5]
console.log( range(5, -5, 2) );     //[5, 3, 1, -1, -3, -5]

コード（修正）

引数が空の時と、1個の時の結果が不満だったので。

const range = function (from, to, step) {
    const length = arguments.length;
    if (length===0) return new Array();

    if (Number.isFinite(from) === false) from = 0;
    if (length===1 && from > 0) to = from, from = 0;

    if (Number.isFinite(to) === false) to = 0;
    if (from === to) return Array.of(to);

    if (Number.isFinite(step) === false || step < 1) step = 1;

    const result = new Array();
    if (from < to) {
        for (; from <= to; from += step) result.push(from);
    } else {
        for (; from >= to; from -= step) result.push(from);
    }
    return result;
};

console.log( range() );             //（新）[]（旧）[0] 

console.log( range(-5) );           //[-5, -4, -3, -2, -1, 0]
console.log( range(5) );            //（新）[0, 1, 2, 3, 4, 5]（旧）[5, 4, 3, 2, 1, 0] 

変更点

• アロー関数はargumentsが使えないのでfunctionに変更
• 引数が空の時、空の配列を返す
• 引数が1個且つ0より大きい時、from->0ではなく0->fromで返す