(function updateLookupFieldSchema() {
    const listWithLookupUrl = 'https://m365x46891638.sharepoint.com/sites/ContractManagement/Lists/Contracts';
    const lookupFieldName = 'LookupToAccounts';
    const lookupSourceListUrl = 'https://m365x46891638.sharepoint.com/sites/ContractManagement/Lists/Accounts';

    const targetUrlObj = new URL(listWithLookupUrl);
    const sourceUrlObj = new URL(lookupSourceListUrl);
    const targetListSR = targetUrlObj.pathname;
    const sourceListSR = sourceUrlObj.pathname;

    const targetWebUrl = extractSiteUrl(listWithLookupUrl);
    const sourceWebUrl = extractSiteUrl(lookupSourceListUrl);

    const ctxTarget = new SP.ClientContext(targetWebUrl);
    const webTarget = ctxTarget.get_web();
    const listTarget = webTarget.getList(targetListSR);
    const field = listTarget.get_fields().getByInternalNameOrTitle(lookupFieldName);

    ctxTarget.load(field, 'SchemaXml', 'Id');
    ctxTarget.executeQueryAsync(onFieldLoaded, onError.bind(null, 'Load field'));

    function onFieldLoaded() {
        const xmlDoc = new DOMParser().parseFromString(field.get_schemaXml(), 'application/xml');
        const fieldNode = xmlDoc.getElementsByTagName('Field')[0];

        const ctxSrc = (sourceWebUrl === targetWebUrl)
            ? ctxTarget
            : new SP.ClientContext(sourceWebUrl);
        const webSource = ctxSrc.get_web();
        const listSource = webSource.getList(sourceListSR);

        ctxSrc.load(listSource, 'Id');
        if (sourceWebUrl !== targetWebUrl) {
            ctxSrc.load(webSource, 'Id');
        }

        ctxSrc.executeQueryAsync(function () {
            const listIdBraced = '{' + listSource.get_id().toString().toUpperCase() + '}';
            fieldNode.setAttribute('List', listIdBraced);

            if (sourceWebUrl !== targetWebUrl) {
                fieldNode.setAttribute('WebId', webSource.get_id().toString().toUpperCase());
            } else {
                if (fieldNode.hasAttribute('WebId')) {
                    fieldNode.removeAttribute('WebId');
                }
            }

            // fieldNode.setAttribute('ShowField', 'InternalNameOfYourColumn');

            const newSchema = new XMLSerializer().serializeToString(xmlDoc);
            field.set_schemaXml(newSchema);
            field.update();

            ctxTarget.executeQueryAsync(
                () => console.log('✅ Lookup field schema updated.'),
                onError.bind(null, 'Update field')
            );
        }, onError.bind(null, 'Load source list'));
    }

    function extractSiteUrl(listUrl) {
        const urlParts = listUrl.split("/");
        if (urlParts.length > 1 && urlParts[urlParts.length - 2].toLowerCase() === "lists") {
            return urlParts.slice(0, urlParts.length - 2).join("/");
        }
        return urlParts.slice(0, urlParts.length - 1).join("/");
    }

    function onError(stage, sender, args) {
        console.error(stage + ' error: ' + args.get_message());
    }
})();