@jrc03c/js-math-tools/src/is-array.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 { isArray } from "./is-array.mjs"
import { normal } from "./normal.mjs"

class SubArray extends Array {}

test("tests that arrays can be identified correctly", () => {
  const selfReferencer = [2, 3, 4]
  selfReferencer.push(selfReferencer)

  const sub = new SubArray()
  sub.push("a")
  sub.push("b")
  sub.push("c")

  const rights = [
    selfReferencer,
    normal(100),
    normal([10, 10]),
    normal([2, 3, 4, 5]),
    sub,
  ]

  forEach(rights, item => {
    expect(isArray(item)).toBe(true)
  })

  const wrongs = [
    0,
    1,
    2.3,
    -2.3,
    Infinity,
    -Infinity,
    NaN,
    "foo",
    true,
    false,
    null,
    undefined,
    Symbol.for("Hello, world!"),
    x => x,
    function (x) {
      return x
    },
    { hello: "world" },
    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(isArray(item)).toBe(false)
  })
})

test("tests that typed arrays are also recognized as arrays", () => {
  const types = [
    BigInt64Array,
    BigUint64Array,
    Float32Array,
    Float64Array,
    Int16Array,
    Int32Array,
    Int8Array,
    Uint16Array,
    Uint32Array,
    Uint8Array,
    Uint8ClampedArray,
  ]

  const buffer = new ArrayBuffer(256)
  expect(isArray(buffer)).toBe(true)

  forEach(types, T => {
    const x = new T(buffer)
    expect(isArray(x)).toBe(true)
  })
})