@jrc03c/js-math-tools/src/is-undefined.test.mjs

some math tools for JS

import { DataFrame, Series } from "./dataframe/index.mjs"
import { expect, test } from "@jrc03c/fake-jest"
import { forEach } from "./for-each.mjs"
import { isUndefined } from "./is-undefined.mjs"

test("checks to see if various things are undefined", () => {
  let x

  expect(isUndefined(x)).toBe(true)
  expect(isUndefined(null)).toBe(true)
  expect(isUndefined(undefined)).toBe(true)

  const selfReferencer = [2, 3, 4]
  selfReferencer.push(selfReferencer)

  const wrongs = [
    0,
    1,
    2.3,
    -2.3,
    Infinity,
    -Infinity,
    NaN,
    "foo",
    true,
    false,
    Symbol.for("Hello, world!"),
    [2, 3, 4],
    [
      [2, 3, 4],
      [5, 6, 7],
    ],
    x => x,
    function (x) {
      return x
    },
    { hello: "world" },
    selfReferencer,
    new Series({ hello: [10, 20, 30, 40, 50] }),
    new DataFrame({ foo: [1, 2, 4, 8, 16], bar: [1, 3, 9, 27, 81] }),
  ]

  forEach(wrongs, item => {
    expect(isUndefined(item)).toBe(false)
  })
})