Line folding breaks surrogate pairs

[HeikoTheissen]

ical-generator/src/_tools.js

Line 93 in d4cd9cd

return line.match(/(.{1,74})/g).join('\r\n ');

Folding an iCalendar line after every 74 characters does not work if the 74th and 75th character form a surrogate pair. iCalendar clients are unable to reconstitute the pair if it is split across two lines.

For example,

'use strict';

const ical = require('ical-generator');
const moment = require('moment');
const cal = ical({domain: 'localhost'});

// overwrite domain
cal.domain('example.com');

const event = cal.createEvent({
    start: moment().add(1, 'hour'),
    end: moment().add(2, 'hours'),
    summary: '0123456789ABCDEF0123456789ABCDEF0123456789ABCDEF0123456789ABCDEF:📞'
});

console.log(cal.toString());

produces output where the telephone symbol is split and rendered by Google Calendar as ...ABCDEF:��. In such cases, the split must happen before the 74th character.

Moreover, even in the absence of surrogate pairs, a line with 74 Unicode characters (which are not all ASCII) can have more than 74 octets and so exceed the limit suggested in the RFC.

[sebbo2002]

🎉 Released in 1.15.4, thank you.