Mjtb-unidata NPM

mjtb-unidata

This module provides an API for looking up characters in the Unicode public character database downloadable at http://www.unicode.org/Public/UNIDATA/UnicodeData.txt.

Here’s an example of how to use it. The example below is a simplification of the unidata command-line interface located in bin/unidata.

// Usage: unidata U+0041 U+2026 U+1F577    # lookup code points
//        unidata quot                     # search for "quot"
//
const UnicodeData = require('mjtb-unidata');
UnicodeData.instance().promise().then(function() {
    var chars = [];
    var re = /U\+[0-9A-F]+/i;
    for(var i = 2; i < process.argv.length; ++i) {
        var arg = process.argv[i];
        if(re.test(arg)) {
            // Lookup character based on code point
            chars.push(UnicodeData.instance().get(Number.parseInt(arg.substring(2), 16)));
        } else {
            // Search for characters matching name
            chars = chars.concat(UnicodeData.instance().find(arg));
        }
    }
    var found = false;
    for(var i = 0; i < chars.length; ++i) {
        var c = chars[i];
        if(c) {
            // E.g., U+0041 (A) LATIN CAPITAL LETTER A [Letter, Uppercase «Lu»]
            var abbr = c.general || UnicodeData.Categories.default;
            var desc = UnicodeData.Category[abbr];
            console.log(`${c} [${desc} «${abbr}»]`);
            found = true;
        }
    }
    if(!found) {
        console.log('No characters found');
    }
});

API

The module’s exports include all of types exposed by the library and a function UnicodeData.instance() that returns a global singleton instance of the UnicodeData class. This class exposes a get(…) method that you can use to look up detailed information about a character given its Unicode code point numeric value. Detailed character information is encapsulated in instances of the UnicodeCharacter which exposes properties for things such as a human-readable name for the character and various flags such as its general category (e.g., Lu meaning “Letter, Uppercase”) and uppercase/lowercase equivalents.

You can also search the database using the UnicodeData.find(…) method by providing either a partial name or by providing a filter function.

The module’s exported UnicodeData instance initializes asynchronously. During this asynchronous initialization, the public Unicode database is downloaded, parsed and cached (valid for one year) in a OS-specific per-user application data directory.

The asynchronous initialization is encapsulated in a Javascript Promise object that you can get via the UnicodeData.promise() method. The value that is passed to any fulfillment handlers will be a reference to the UnicodeData object.

In addition to the Promise-based API, detailed information about the initialization of the module’s exported instance of UnicodeData can be obtained via an event-based API. The UnicodeData class inherits from the standard Node.js EventEmitter class and exposes an on(…) method that may be used to bind handlers to events. There are two terminal completion events: the ready event is emitted when the UnicodeData instance is successfully initialized; the error event is emitted if initialization fails. There are two intermediate progress events: the readystatechange event is emitted multiple times as initialization processed from one sub-task to another progress; the download event is emitted at most once, when a fresh copy of the public Unicode database needs to be downloaded.

CLI

Two command-line interfaces are available:

unidata lets you look up the character information given its code point or a partial match to its name.
unichar writes to standard output characters given their code points.

Refer to the man(1) pages for these commands for additional information.