escape html in a string - typescript

escape-html.ts

export function escapeHtml(str: string) {
    let html = '';
    let matchIndex: number | undefined;
    let lastIndex = 0;
    let char: string;
    while (true) {
        matchIndex = regex.exec(str)?.index;
        if (matchIndex === undefined) break;
        html += str.slice(lastIndex, matchIndex);
        char = str[matchIndex];
        html += escapeMap[char];
        lastIndex = matchIndex + 1;
    }
    html += str.slice(lastIndex);
    return html
}