Pagination Test

.gitignore

node_modules/
package-lock.json

package.json

{
  "name": "pagination",
  "version": "1.0.0",
  "description": "testing pagination",
  "repository": "https://gist.github.com/094ecd182a254f67530f58a06784abb9",
  "license": "ISC",
  "author": "Joe Maller <joe@ideasonpurpose.com>",
  "main": "paginate.js",
  "scripts": {
    "test": "jest",
    "watch": "jest --watchAll"
  },
  "devDependencies": {
    "jest": "^24.8.0"
  }
}

paginate.js

function paginate(thisPage, allLinks = 12, showLinks = 5) {
  const arr = [...Array(allLinks + 1).keys()].slice(1);

  let start = Math.max(thisPage - Math.ceil(showLinks / 2), 0);
  start = allLinks - start < showLinks ? allLinks - showLinks : start;
  const end = start + showLinks; // in PHP this is just showLinks
  return arr.slice(start, end);
}

module.exports = paginate;

paginate.test.js

const paginate = require("./paginate");

test("1/12", () => {
  expect(paginate(2, 12)).toEqual([1, 2, 3, 4, 5]);
});

test("2/12", () => {
  expect(paginate(2, 12)).toEqual([1, 2, 3, 4, 5]);
});

test("4/12", () => {
  expect(paginate(4, 12)).toEqual([2, 3, 4, 5, 6]);
});

test("5/12", () => {
  expect(paginate(5, 12)).toEqual([3, 4, 5, 6, 7]);
});

test("8/12", () => {
  expect(paginate(8, 12)).toEqual([6, 7, 8, 9, 10]);
});
test("9/12", () => {
  expect(paginate(9, 12)).toEqual([7, 8, 9, 10, 11]);
});

test("10/12", () => {
  expect(paginate(10, 12)).toEqual([8, 9, 10, 11, 12]);
});

test("11/12", () => {
  expect(paginate(11, 12)).toEqual([8, 9, 10, 11, 12]);
});

test("12/12", () => {
  expect(paginate(12, 12)).toEqual([8, 9, 10, 11, 12]);
});

test("1/12 (4)", () => {
  expect(paginate(1, 12, 4)).toEqual([1, 2, 3, 4]);
});

test("3/12 (4)", () => {
  expect(paginate(3, 12, 4)).toEqual([2, 3, 4, 5]);
});

test("10/12 (4)", () => {
  expect(paginate(10, 12, 4)).toEqual([9, 10, 11, 12]);
});

test("12/12 (4)", () => {
  expect(paginate(12, 12, 4)).toEqual([9, 10, 11, 12]);
});

test("1/5", () => {
  expect(paginate(1, 5)).toEqual([1, 2, 3, 4, 5]);
});

test("3/5", () => {
  expect(paginate(3, 5)).toEqual([1, 2, 3, 4, 5]);
});

test("4/5", () => {
  expect(paginate(4, 5)).toEqual([1, 2, 3, 4, 5]);
});
test("1/6", () => {
  expect(paginate(1, 6)).toEqual([1, 2, 3, 4, 5]);
});

test("3/6", () => {
  expect(paginate(3, 6)).toEqual([1, 2, 3, 4, 5]);
});

test("4/6", () => {
  expect(paginate(4, 6)).toEqual([2, 3, 4, 5, 6]);
});

test("5/6", () => {
  expect(paginate(5, 6)).toEqual([2, 3, 4, 5, 6]);
});