User:LOL/sandbox.js

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This user script seems to have a documentation page at User:LOL/sandbox.

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function lolsandbox() {
    var xmlhttp;
    if (window.XMLHttpRequest) {
        xmlhttp=new XMLHttpRequest();
    } else {
        xmlhttp=new ActiveXObject("Microsoft.XMLHTTP");
    }
    xmlhttp.onreadystatechange = function() {
        if (xmlhttp.readyState == 4 && xmlhttp.status == 200) {
            document.getElementById('wpTextbox1').value = xmlhttp.responseText;
        }
    }
    var url = prompt('Enter the URL of a page whose source shall be fetched', 'URL');
    xmlhttp.open('GET', url, true);
    xmlhttp.send();
}

$(function() {
    if (document.forms.editform) {
        mw.util.addPortletLink('p-tb', 'javascript:lolsandbox()', 'Sandbox', 't-mmarecordcolumns', 'LOL', '', '');
    }
});