tipograph/src/presets/hyphens.js

A little javascript library and command line tool that makes your written content more typographically correct.

/// #### hyphens
///
/// Hyphens are present on our keyboards and are used mostly to separate multipart words ("cost-effective") or
/// multiword phrases which need to be together ("high-school grades"). Dashes come in two sizes: en dash and em dash.
/// En dash is used instead of hyphen in number ranges ("1-5"), or when two consecutive hyphens are found. Em dash is
/// use when three consecutive hyphens are found. Both can be used as a break in a sentence ("tipograph - even if it's
/// just a set of simple rules - can improve typography in your content"). Whether en dash or em dash will be used for
/// this case depends on the setting of the language or it can be overridden by `dash: 'en' | 'em'` in tipograph
/// options.

export default function (language, options) {
    var enRule = [/\u0020+-\u0020+/g, '\u0020\u2013\u0020'];
    var emRule = [/\u0020+-\u0020+/g, '\u200a\u2014\u200a'];

    var dash = options.dash || language.dash;

    var dashRule = enRule;
    switch (dash) {
        case 'en':
            dashRule = enRule;
            break;
        case 'em':
            dashRule = emRule;
            break;
        default:
            console.warn('invalid option `dash: ' + dash + '`');
            break;
    }

    // NOTE: consecutive hyphens (2 or 3) are always transformed, because it's a user's choice, even if it is bad in the
    //       context
    return [
        // em dash
        [/\u0020*---(\r?\n|$)/g, '\u200a\u2014$1'],
        [/\u0020*---\u0020*/g, '\u200a\u2014\u200a'],
        // en dash
        [/--/g, '\u2013'],
        // number range
        [/(\d)-(\d)/g, '$1\u2013$2'],
        // default dash
        dashRule
    ];
}

export function tests(language) {
    var dash = ({ en: '\u0020\u2013\u0020', em: '\u200a\u2014\u200a' })[language.dash];

    return [
        {
            description: 'two consecutive hyphens surrounded by whitespaces into en dash',
            input: 'lorem -- ipsum',
            expected: 'lorem \u2013 ipsum'
        },
        {
            description: 'keep two consecutive hyphens if not surrounded by whitespaces',
            input: 'lorem--ipsum --dolor',
            expected: 'lorem\u2013ipsum \u2013dolor'
        },
        {
            description: 'three consecutive hyphens into em dash',
            input: 'lorem --- ipsum---dolor',
            expected: 'lorem\u200a\u2014\u200aipsum\u200a\u2014\u200adolor'
        },
        {
            description: 'three consecutive hyphens at the end of line or input into em dash',
            input: 'lorem ipsum---\nlorem ipsum---',
            expected: 'lorem ipsum\u200a\u2014\nlorem ipsum\u200a\u2014'
        },
        {
            description: 'hyphen surrounded by whitespaces into default dash',
            input: 'lorem - ipsum',
            expected: 'lorem' + dash + 'ipsum'
        },
        {
            description: 'keep hyphen if not surrounded by whitespaces',
            input: 'lorem-ipsum -dolor',
            expected: 'lorem-ipsum -dolor'
        },
        {
            description: 'hyphen surrounded by numbers into en dash',
            input: '1-5',
            expected: '1\u20135'
        },
        {
            description: 'take only word spaces as possible whitespaces in hypen to dash rule',
            input: 'lorem -\nipsum lorem\n- ipsum',
            expected: 'lorem -\nipsum lorem\n- ipsum'
        }
    ];
}