https://www.ithinkmagazine.it/wp-content/plugins/advanced-invisible-anti-spam/includes/aia.js

1function update_token() {
2	if ( this.readyState === 4 ) {
3		if ( this.status >= 200 && this.status < 400 ) {
4			var response = JSON.parse( this.responseText );
5
6			var element = document.createElement( 'input' );
7			element.type = 'hidden';
8			element.name = response.field;
9			element.value = response.value;
10
11			var temp = document.getElementById( 'aia_placeholder' );
12			var form = temp.form;
13			var inputs = form.getElementsByTagName( 'input' );
14			var index = Math.floor( Math.random() * ( inputs.length -1 ) );
15
16			inputs[ index ].parentNode.appendChild( element );
17			form.removeChild( temp );
18		}
19	}
20}
21
22if ( null !== document.getElementById( 'aia_placeholder' ) ) {
23	var data	= 'action=aia_field_update';
24	var request = window.XMLHttpRequest ? new XMLHttpRequest() : new ActiveXObject( 'Microsoft.XMLHTTP' );
25	request.open( 'POST', AIA.ajaxurl, true );
26	request.setRequestHeader( 'Content-Type', 'application/x-www-form-urlencoded; charset=UTF-8' );
27	request.onreadystatechange = update_token;
28	request.send( data );
29}