add top-level property

dynamic Function(dynamic feature, dynamic sub, dynamic script, dynamic language) add

Implementation

Substitution.prototype.add = function(feature, sub, script, language) {
    if (/ss\d\d/.test(feature)) {
        // ss01 - ss20
        return this.addSingle(feature, sub, script, language);
    }
    switch (feature) {
        case 'aalt':
        case 'salt':
            if (typeof sub.by === 'number') {
                return this.addSingle(feature, sub, script, language);
            }
            return this.addAlternate(feature, sub, script, language);
        case 'dlig':
        case 'liga':
        case 'rlig':
            return this.addLigature(feature, sub, script, language);
        case 'ccmp':
            if (sub.by instanceof Array) {
                return this.addMultiple(feature, sub, script, language);
            }
            return this.addLigature(feature, sub, script, language);
    }
    return undefined;
};