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export type PagenationProp = {
now: number,
max: number,
between: number,
}
export function createPagenation(prop: PagenationProp) {
if (prop.between < 0) {
throw new Error(`betweenは0以上にして下さい`);
}
if (prop.max < 0) {
throw new Error(`maxは0以上にして下さい`);
}
if (prop.now < 0) {
throw new Error(`nowは0以上にして下さい`);
}
if (prop.max < prop.now) {
throw new Error(`nowの値はmaxと同じか、より小さな値にして下さい. now:${prop.now} , max:${prop.max}`);
}
if (prop.max == 0) {
return [];
}
const MIN = 1;
// 左・中・右の3ブロックの変数を作成
const blockLeft = MIN;
let blockMiddle = [
...Array.from({ length: prop.between }).map((_, index) => {
const i = prop.now - prop.between + index;
return i;
}),
prop.now,
...Array.from({ length: prop.between }).map((_, index) => {
const i = prop.now + index + 1;
return i;
}),
];
blockMiddle = blockMiddle.filter(i => {
if (i <= blockLeft) {
return false;
}
if (prop.max <= i) {
return false;
}
return true;
});
const blockRight = prop.max;
type A = { type: "back", key: string, link: number | null };
type B = { type: "next", key: string, link: number | null };
type C = { type: "sp", key: string, };
type D = { type: "num", key: string, link: number | null, num: number }
// 結合を作成
const pageIdList: (A | B | C | D)[] = [];
{
// 左戻る矢印
if (prop.now == MIN) {
pageIdList.push({ type: "back", key: "back", link: null });
} else {
pageIdList.push({ type: "back", key: "back", link: prop.now - 1 });
}
// 最初のページ
pageIdList.push({ type: "num", key: `p-${blockLeft}`, link: blockLeft, num: blockLeft });
let lastPageId = blockLeft;
// 左と中の間の…を入れるかどうか
if (0 < blockMiddle.length && lastPageId + 1 != blockMiddle[0]) {
pageIdList.push({ type: "sp", key: "sp-left" });
}
blockMiddle.forEach(m => {
pageIdList.push({ type: "num", key: `p-${m}`, link: m, num: m });
lastPageId = m;
});
if (0 < blockMiddle.length && lastPageId + 1 != blockRight) {
// 最後のページ
pageIdList.push({ type: "sp", key: "sp-right" });
}
if (lastPageId != blockRight) {
pageIdList.push({ type: "num", key: `p-${blockRight}`, link: blockRight, num: blockRight });
lastPageId = blockRight;
}
// 右矢印
if (prop.now == prop.max) {
pageIdList.push({ type: "next", key: "next", link: null });
} else {
pageIdList.push({ type: "next", key: "next", link: prop.now + 1 });
}
pageIdList.forEach(p => {
if ("link" in p && p.link == prop.now) {
p.link = null;
}
})
}
return pageIdList
}
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