const regex = /<div.+?>(.+)?<\/div>/si;
// Alternative syntax using RegExp constructor
// const regex = new RegExp('<div.+?>(.+)?<\\\/div>', 'si')
const str = `<h3>Programma en uitslagen</h3>
<table width="100%">
<tr>
<th>ronde</th>
<th>dag</th>
<th>datum</th>
<th></th>
<th>thuis</th>
<th>uit</th>
<th> </th>
<th colspan="1"> </th>
<th colspan="2">uitslag</th>
<th>ct</th>
<th>cu</th>
<th> </th>
</tr>
<tr>
<td class="getal">1</td>
<td>Ma.</td>
<td>22-08-2016 19:30</td>
<td>
<div title="Add to Calendar" class="addthisevent">
<span class="start">22/08/2016 19:30:00</span>
<span class="end">22/08/2016 22:30:00</span>
<span class="timezone">Europe/Amsterdam</span>
<span class="title">Kamperduin 1 vs Kamperduin 2</span>
<span class="description">Biljartwedstrijd 3Bnd B1 - Ronde 1</span>
<span class="location"></span>
<span class="organizer">KNBB</span>
<span class="organizer_email"></span>
<span class="all_day_event">false</span>
<span class="date_format">DD/MM/YYYY</span>
<span class="alarm_reminder">60</span>
</div>
</td>
<td><a href="http://www.biljartpoint.nl/index.php?page=teamdetail&team_id=29629&compid=2470&poule=A&district=57">Kamperduin 1</a></td>
<td><a href="http://www.biljartpoint.nl/index.php?page=teamdetail&team_id=29627&compid=2470&poule=A&district=57">Kamperduin 2</a></td>
<td></td>
<td> </td>
<td></td>
<td> </td>
<td> </td>
<td> </td>
<td> </td>
</tr>`;
const subst = ` gdgf`;
// The substituted value will be contained in the result variable
const result = str.replace(regex, subst);
console.log('Substitution result: ', result);
Please keep in mind that these code samples are automatically generated and are not guaranteed to work. If you find any syntax errors, feel free to submit a bug report. For a full regex reference for JavaScript, please visit: https://developer.mozilla.org/en/docs/Web/JavaScript/Guide/Regular_Expressions