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741 BJavaScriptView Raw
1'use strict';
2var stripAnsi = require('strip-ansi');
3var codePointAt = require('code-point-at');
4var isFullwidthCodePoint = require('is-fullwidth-code-point');
5
6// https://github.com/nodejs/io.js/blob/cff7300a578be1b10001f2d967aaedc88aee6402/lib/readline.js#L1345
7module.exports = function (str) {
8 if (typeof str !== 'string' || str.length === 0) {
9 return 0;
10 }
11
12 var width = 0;
13
14 str = stripAnsi(str);
15
16 for (var i = 0; i < str.length; i++) {
17 var code = codePointAt(str, i);
18
19 // ignore control characters
20 if (code <= 0x1f || (code >= 0x7f && code <= 0x9f)) {
21 continue;
22 }
23
24 // surrogates
25 if (code >= 0x10000) {
26 i++;
27 }
28
29 if (isFullwidthCodePoint(code)) {
30 width += 2;
31 } else {
32 width++;
33 }
34 }
35
36 return width;
37};