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nodejs/test/parallel/test-icu-stringwidth.js
James M Snell 72547fe28d readline: use icu based string width calculation
Rather than the pseudo-wcwidth impl used currently, use the ICU
character properties database to calculate string width and
determine if a character is full width or not. This allows the
algorithm to correctly identify emoji's as full width, ensures
the algorithm will continue to fucntion properly as new unicode
codepoints are added, and it's faster.

This was originally part of a proposal to add a new unicode module,
but has been split out.

Refs: https://github.com/nodejs/node/pull/8075
PR-URL: https://github.com/nodejs/node/pull/9040
Reviewed-By: Ben Noordhuis <info@bnoordhuis.nl>
Reviewed-By: Steven R Loomis <srloomis@us.ibm.com>
2016-10-25 09:00:45 -07:00

44 lines
1.9 KiB
JavaScript

// Flags: --expose_internals
'use strict';
const common = require('../common');
const assert = require('assert');
const readline = require('internal/readline');
if (!process.binding('config').hasIntl) {
common.skip('missing intl... skipping test');
return;
}
// Test column width
assert.strictEqual(readline.getStringWidth('a'), 1);
assert.strictEqual(readline.getStringWidth('丁'), 2);
assert.strictEqual(readline.getStringWidth('\ud83d\udc78\ud83c\udfff'), 2);
assert.strictEqual(readline.getStringWidth('👅'), 2);
assert.strictEqual(readline.getStringWidth('\n'), 0);
assert.strictEqual(readline.getStringWidth('\u200Ef\u200F'), 1);
assert.strictEqual(readline.getStringWidth(97), 1);
// The following is an emoji sequence. In some implementations, it is
// represented as a single glyph, in other implementations as a sequence
// of individual glyphs. By default, the algorithm will assume the single
// glyph interpretation and return a value of 2. By passing the
// expandEmojiSequence: true option, each component will be counted
// individually.
assert.strictEqual(readline.getStringWidth('👩‍👩‍👧‍👧'), 2);
assert.strictEqual(
readline.getStringWidth('👩‍👩‍👧‍👧', {expandEmojiSequence: true}), 8);
// By default, unicode characters whose width is considered ambiguous will
// be considered half-width. For these characters, getStringWidth will return
// 1. In some contexts, however, it is more appropriate to consider them full
// width. By default, the algorithm will assume half width. By passing
// the ambiguousAsFullWidth: true option, ambiguous characters will be counted
// as 2 columns.
assert.strictEqual(readline.getStringWidth('\u01d4'), 1);
assert.strictEqual(
readline.getStringWidth('\u01d4', {ambiguousAsFullWidth: true}), 2);
// Control chars and combining chars are zero
assert.strictEqual(readline.getStringWidth('\u200E\n\u220A\u20D2'), 1);