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JavaScript

/**
* Observe how the user enters content into the comment form in order to determine whether it's a bot or not.
*
* Note that no actual input is being saved here, only counts and timings between events.
*/
( function() {
// Passive event listeners are guaranteed to never call e.preventDefault(),
// but they're not supported in all browsers. Use this feature detection
// to determine whether they're available for use.
var supportsPassive = false;
try {
var opts = Object.defineProperty( {}, 'passive', {
get : function() {
supportsPassive = true;
}
} );
window.addEventListener( 'testPassive', null, opts );
window.removeEventListener( 'testPassive', null, opts );
} catch ( e ) {}
function init() {
var input_begin = '';
var keydowns = {};
var lastKeyup = null;
var lastKeydown = null;
var keypresses = [];
var modifierKeys = [];
var correctionKeys = [];
var lastMouseup = null;
var lastMousedown = null;
var mouseclicks = [];
var mousemoveTimer = null;
var lastMousemoveX = null;
var lastMousemoveY = null;
var mousemoveStart = null;
var mousemoves = [];
var touchmoveCountTimer = null;
var touchmoveCount = 0;
var lastTouchEnd = null;
var lastTouchStart = null;
var touchEvents = [];
var scrollCountTimer = null;
var scrollCount = 0;
var correctionKeyCodes = [ 'Backspace', 'Delete', 'ArrowUp', 'ArrowDown', 'ArrowLeft', 'ArrowRight', 'Home', 'End', 'PageUp', 'PageDown' ];
var modifierKeyCodes = [ 'Shift', 'CapsLock' ];
var forms = document.querySelectorAll( 'form[method=post]' );
for ( var i = 0; i < forms.length; i++ ) {
var form = forms[i];
var formAction = form.getAttribute( 'action' );
// Ignore forms that POST directly to other domains; these could be things like payment forms.
if ( formAction ) {
// Check that the form is posting to an external URL, not a path.
if ( formAction.indexOf( 'http://' ) == 0 || formAction.indexOf( 'https://' ) == 0 ) {
if ( formAction.indexOf( 'http://' + window.location.hostname + '/' ) != 0 && formAction.indexOf( 'https://' + window.location.hostname + '/' ) != 0 ) {
continue;
}
}
}
form.addEventListener( 'submit', function () {
var ak_bkp = prepare_timestamp_array_for_request( keypresses );
var ak_bmc = prepare_timestamp_array_for_request( mouseclicks );
var ak_bte = prepare_timestamp_array_for_request( touchEvents );
var ak_bmm = prepare_timestamp_array_for_request( mousemoves );
var input_fields = {
// When did the user begin entering any input?
'ak_bib': input_begin,
// When was the form submitted?
'ak_bfs': Date.now(),
// How many keypresses did they make?
'ak_bkpc': keypresses.length,
// How quickly did they press a sample of keys, and how long between them?
'ak_bkp': ak_bkp,
// How quickly did they click the mouse, and how long between clicks?
'ak_bmc': ak_bmc,
// How many mouseclicks did they make?
'ak_bmcc': mouseclicks.length,
// When did they press modifier keys (like Shift or Capslock)?
'ak_bmk': modifierKeys.join( ';' ),
// When did they correct themselves? e.g., press Backspace, or use the arrow keys to move the cursor back
'ak_bck': correctionKeys.join( ';' ),
// How many times did they move the mouse?
'ak_bmmc': mousemoves.length,
// How many times did they move around using a touchscreen?
'ak_btmc': touchmoveCount,
// How many times did they scroll?
'ak_bsc': scrollCount,
// How quickly did they perform touch events, and how long between them?
'ak_bte': ak_bte,
// How many touch events were there?
'ak_btec' : touchEvents.length,
// How quickly did they move the mouse, and how long between moves?
'ak_bmm' : ak_bmm
};
for ( var field_name in input_fields ) {
var field = document.createElement( 'input' );
field.setAttribute( 'type', 'hidden' );
field.setAttribute( 'name', field_name );
field.setAttribute( 'value', input_fields[ field_name ] );
this.appendChild( field );
}
}, supportsPassive ? { passive: true } : false );
form.addEventListener( 'keydown', function ( e ) {
// If you hold a key down, some browsers send multiple keydown events in a row.
// Ignore any keydown events for a key that hasn't come back up yet.
if ( e.key in keydowns ) {
return;
}
var keydownTime = ( new Date() ).getTime();
keydowns[ e.key ] = [ keydownTime ];
if ( ! input_begin ) {
input_begin = keydownTime;
}
// In some situations, we don't want to record an interval since the last keypress -- for example,
// on the first keypress, or on a keypress after focus has changed to another element. Normally,
// we want to record the time between the last keyup and this keydown. But if they press a
// key while already pressing a key, we want to record the time between the two keydowns.
var lastKeyEvent = Math.max( lastKeydown, lastKeyup );
if ( lastKeyEvent ) {
keydowns[ e.key ].push( keydownTime - lastKeyEvent );
}
lastKeydown = keydownTime;
}, supportsPassive ? { passive: true } : false );
form.addEventListener( 'keyup', function ( e ) {
if ( ! ( e.key in keydowns ) ) {
// This key was pressed before this script was loaded, or a mouseclick happened during the keypress, or...
return;
}
var keyupTime = ( new Date() ).getTime();
if ( 'TEXTAREA' === e.target.nodeName || 'INPUT' === e.target.nodeName ) {
if ( -1 !== modifierKeyCodes.indexOf( e.key ) ) {
modifierKeys.push( keypresses.length - 1 );
} else if ( -1 !== correctionKeyCodes.indexOf( e.key ) ) {
correctionKeys.push( keypresses.length - 1 );
} else {
// ^ Don't record timings for keys like Shift or backspace, since they
// typically get held down for longer than regular typing.
var keydownTime = keydowns[ e.key ][0];
var keypress = [];
// Keypress duration.
keypress.push( keyupTime - keydownTime );
// Amount of time between this keypress and the previous keypress.
if ( keydowns[ e.key ].length > 1 ) {
keypress.push( keydowns[ e.key ][1] );
}
keypresses.push( keypress );
}
}
delete keydowns[ e.key ];
lastKeyup = keyupTime;
}, supportsPassive ? { passive: true } : false );
form.addEventListener( "focusin", function ( e ) {
lastKeydown = null;
lastKeyup = null;
keydowns = {};
}, supportsPassive ? { passive: true } : false );
form.addEventListener( "focusout", function ( e ) {
lastKeydown = null;
lastKeyup = null;
keydowns = {};
}, supportsPassive ? { passive: true } : false );
}
document.addEventListener( 'mousedown', function ( e ) {
lastMousedown = ( new Date() ).getTime();
}, supportsPassive ? { passive: true } : false );
document.addEventListener( 'mouseup', function ( e ) {
if ( ! lastMousedown ) {
// If the mousedown happened before this script was loaded, but the mouseup happened after...
return;
}
var now = ( new Date() ).getTime();
var mouseclick = [];
mouseclick.push( now - lastMousedown );
if ( lastMouseup ) {
mouseclick.push( lastMousedown - lastMouseup );
}
mouseclicks.push( mouseclick );
lastMouseup = now;
// If the mouse has been clicked, don't record this time as an interval between keypresses.
lastKeydown = null;
lastKeyup = null;
keydowns = {};
}, supportsPassive ? { passive: true } : false );
document.addEventListener( 'mousemove', function ( e ) {
if ( mousemoveTimer ) {
clearTimeout( mousemoveTimer );
mousemoveTimer = null;
}
else {
mousemoveStart = ( new Date() ).getTime();
lastMousemoveX = e.offsetX;
lastMousemoveY = e.offsetY;
}
mousemoveTimer = setTimeout( function ( theEvent, originalMousemoveStart ) {
var now = ( new Date() ).getTime() - 500; // To account for the timer delay.
var mousemove = [];
mousemove.push( now - originalMousemoveStart );
mousemove.push(
Math.round(
Math.sqrt(
Math.pow( theEvent.offsetX - lastMousemoveX, 2 ) +
Math.pow( theEvent.offsetY - lastMousemoveY, 2 )
)
)
);
if ( mousemove[1] > 0 ) {
// If there was no measurable distance, then it wasn't really a move.
mousemoves.push( mousemove );
}
mousemoveStart = null;
mousemoveTimer = null;
}, 500, e, mousemoveStart );
}, supportsPassive ? { passive: true } : false );
document.addEventListener( 'touchmove', function ( e ) {
if ( touchmoveCountTimer ) {
clearTimeout( touchmoveCountTimer );
}
touchmoveCountTimer = setTimeout( function () {
touchmoveCount++;
}, 500 );
}, supportsPassive ? { passive: true } : false );
document.addEventListener( 'touchstart', function ( e ) {
lastTouchStart = ( new Date() ).getTime();
}, supportsPassive ? { passive: true } : false );
document.addEventListener( 'touchend', function ( e ) {
if ( ! lastTouchStart ) {
// If the touchstart happened before this script was loaded, but the touchend happened after...
return;
}
var now = ( new Date() ).getTime();
var touchEvent = [];
touchEvent.push( now - lastTouchStart );
if ( lastTouchEnd ) {
touchEvent.push( lastTouchStart - lastTouchEnd );
}
touchEvents.push( touchEvent );
lastTouchEnd = now;
// Don't record this time as an interval between keypresses.
lastKeydown = null;
lastKeyup = null;
keydowns = {};
}, supportsPassive ? { passive: true } : false );
document.addEventListener( 'scroll', function ( e ) {
if ( scrollCountTimer ) {
clearTimeout( scrollCountTimer );
}
scrollCountTimer = setTimeout( function () {
scrollCount++;
}, 500 );
}, supportsPassive ? { passive: true } : false );
}
/**
* For the timestamp data that is collected, don't send more than `limit` data points in the request.
* Choose a random slice and send those.
*/
function prepare_timestamp_array_for_request( a, limit ) {
if ( ! limit ) {
limit = 100;
}
var rv = '';
if ( a.length > 0 ) {
var random_starting_point = Math.max( 0, Math.floor( Math.random() * a.length - limit ) );
for ( var i = 0; i < limit && i < a.length; i++ ) {
rv += a[ random_starting_point + i ][0];
if ( a[ random_starting_point + i ].length >= 2 ) {
rv += "," + a[ random_starting_point + i ][1];
}
rv += ";";
}
}
return rv;
}
if ( document.readyState !== 'loading' ) {
init();
} else {
document.addEventListener( 'DOMContentLoaded', init );
}
})();