Deno port of spark - https://github.com/holman/spark

spark.ts

/**
 * spark - https://github.com/holman/spark
 *
 * The MIT License
 * Copyright (c) Zach Holman, https://zachholman.com
 */
import { parse } from "https://deno.land/std@v0.30.0/flags/mod.ts";

export function spark(...nums: number[]): string {
  let min = Infinity;
  let max = 0;
  for (const n of nums) {
    if (n < min) {
      min = n;
    }
    if (n > max) {
      max = n;
    }
  }

  let ticks = ["▁", "▂", "▃", "▄", "▅", "▆", "▇", "█"];
  if (min === max) {
    ticks = ["▅", "▆"];
  }

  let f = ((max - min) << 8) / (ticks.length - 1);
  if (f < 1) {
    f = 1;
  }

  return nums.map(n => ticks[(((n - min) << 8) / f) | 0]).join("");
}

if (import.meta.main) {
  main();
}

async function main() {
  const args = parse(Deno.args, {
    boolean: ["help"],
    alias: {
      help: ["h"]
    }
  });

  if ((Deno.isTTY().stdin && !args._.length) || args.h || args.help) {
    printUsage();
    Deno.exit(0);
  }

  if (!Deno.isTTY().stdin) {
    const input = await Deno.readAll(Deno.stdin);
    args._ = [new TextDecoder().decode(input)];
  }

  let nums = [] as number[];
  for (const arg of args._) {
    const ns = arg.split(/[\s,]+/).map(n => +n | 0);
    nums = nums.concat(ns);
  }

  console.log(spark(...nums));

  function printUsage() {
    console.error(`USAGE:
  spark [-h|--help] VALUE,...

EXAMPLES:
  spark 1 5 22 13 53
  ▁▁▃▂█
  spark 0,30,55,80,33,150
  ▁▂▃▄▂█
  echo 9 13 5 17 1 | spark
  ▄▆▂█▁`);
  }
}

spark_test.ts

import {
  test,
  assert,
  assertEquals
} from "https://deno.land/std@v0.30.0/testing/mod.ts";

test(async function it_shows_help_with_no_argv() {
  const { code, err } = await graph();
  assertEquals(code, 0);
  assert(err.includes("USAGE"));
});

test(async function it_graphs_argv_data() {
  const { out } = await graph("1,5,22,13,5");
  assertEquals(out, "▁▂█▅▂\n");
});

test(async function it_charts_pipe_data() {
  const { out } = await graph("0,30,55,80,33,150", { pipe: true });
  assertEquals(out, "▁▂▃▄▂█\n");
});

test(async function it_charts_spaced_data() {
  const { out } = await graph("0 30 55 80 33 150");
  assertEquals(out, "▁▂▃▄▂█\n");
});

test(async function it_charts_way_spaced_data() {
  const { out } = await graph("0 30               55 80 33     150");
  assertEquals(out, "▁▂▃▄▂█\n");
});

test(async function it_handles_decimals() {
  const { out } = await graph("5.5,20");
  assertEquals(out, "▁█\n");
});

test(async function it_charts_100_lt_300() {
  const { out } = await graph("1,2,3,4,100,5,10,20,50,300");
  assertEquals(out, "▁▁▁▁▃▁▁▁▂█\n");
});

test(async function it_charts_50_lt_100() {
  const { out } = await graph("1,50,100");
  assertEquals(out, "▁▄█\n");
});

test(async function it_charts_4_lt_8() {
  const { out } = await graph("2,4,8");
  assertEquals(out, "▁▃█\n");
});

test(async function it_charts_no_tier_0() {
  const { out } = await graph("1,2,3,4,5");
  assertEquals(out, "▁▂▄▆█\n");
});

test(async function it_equalizes_at_midtier_on_same_data() {
  const { out } = await graph("1,1,1,1");
  assertEquals(out, "▅▅▅▅\n");
});

// Test util

const __SCRIPT__ = import.meta.url.replace("_test", "");
const decoder = new TextDecoder();
const encoder = new TextEncoder();

async function graph(
  data?: string,
  { pipe = false } = {}
): Promise<{ code: number; out: string; err: string }> {
  const args = ["deno", "run", __SCRIPT__];
  if (!pipe && data) {
    args.push(data);
  }
  const p = Deno.run({
    args,
    stdin: pipe ? "piped" : "inherit",
    stdout: "piped",
    stderr: "piped"
  });
  if (pipe) {
    await p.stdin.write(encoder.encode(data));
    p.stdin.close();
  }
  const { code } = await p.status();
  const out = decoder.decode(await p.output());
  const err = decoder.decode(await p.stderrOutput());
  p.close();
  return { code, out, err };
}