ASCIIfy–Hexify: A bookmarklet to find a character’s ASCII and hexadecimal value

asciify-hexify.js

/**
 * ASCIIfy–Hexify bookmarklet
 * v1.0.0
 *
 * Authors:      Lucas Larson, 2017–
 *               Steve Kangas, 1998
 *
 * Description:  This is the JavaScript behind a bookmarklet to obtain the
 *               ASCII₁₀ value and hexadecimal value of any single character.
 *
 * Installation: See bottom
 *
 * Use:          Tap the bookmarklet, enter any single character – lowercase n,
 *               for example – and the bookmarklet returns n’s ASCII and
 *               hexadecimal values with the following output:
 *                   The ASCII number for “n” is 110,
 *                   and its hexadecimal value is 6E.
 *
 *
 * Credit to     For
 * David Rubin   Confidence
 * Steve Kangas  Character to ASCII bookmarklet  http://bookmarklets.com/tools/design
 * Travis Decker “hexify” instead of “hexafy”
 * John Tantalo  The bookmarklet-as-a-gist idea  https://gist.github.com/tantalor/202523
 * Chris Zarate  Bookmarkleter (with IIFE-fier!) https://chriszarate.github.io/bookmarkleter
 * Joey Twiddle  Easing bookmarklet development  https://stackoverflow.com/a/4488511
 */

// the variable below “‘window’ is not defined” unless the
// browser environment is specified with “/* eslint-env browser */”
// via Carles Alcolea https://stackoverflow.com/a/55198538
/* eslint-env browser */

// Opt out of JavaScript’s Sloppy Mode
"use strict";

// Anonymize the function
void (function () {
  // “Kangas” ends in s but isn’t plural, so we’ll add an apostrophe as well as
  // the letter s for the possessive
  // Steve Kangas’s “p5VgU2z1” becomes “asciify”
  var asciify = window.prompt("Enter a character:", "");

  // avoid NaN output by executing only if asciify has a value
  if (asciify) {
    // forbid entries of more than one character
    if (asciify.length > 1) {
      window.alert("Please enter only one character.");
    } else {
      window.alert(
        "The ASCII number for “" +
          asciify +
          "” is " +
          asciify.charCodeAt(0) +
          ",\nand its hexadecimal value is " +
          // .toString(16) via Matt Dunlap https://stackoverflow.com/a/57805
          // .toUpperCase() via Fabio Ferrari https://stackoverflow.com/a/6680530
          asciify.charCodeAt(0).toString(16).toUpperCase() +
          ".",
      );
    }
  }

  // Installing bookmarklets is famously tricky (see
  // https://mreidsma.github.io/bookmarklets/installing ), but when you’re ready,
  // the URI to enter into the bookmark’s address field is everything on the line
  // between the /* and the */
})();

/*
javascript:'use%20strict';void%20function(){var%20asciify=window.prompt('Enter%20a%20character:','');asciify%26%26(asciify.length%3E1%3Fwindow.alert('Please%20enter%20only%20one%20character.'):window.alert('The%20ASCII%20number%20for%20\u201C'+asciify+'\u201D%20is%20'+asciify.charCodeAt(0)+',\nand%20its%20hexadecimal%20value%20is%20'+asciify.charCodeAt(0).toString(16).toUpperCase()+'.'))}();
*/