mTurk HIT Fullscreen Crosshair CSS (as Userscript)

Userscript adapatation (and improvement) of code found at https://codepen.io/michaelsboost/pen/fnizu - applied to mTurk.

You will need to install an extension such as Tampermonkey, Greasemonkey or Violentmonkey to install this script.

You will need to install an extension such as Tampermonkey or Violentmonkey to install this script.

You will need to install an extension such as Tampermonkey or Violentmonkey to install this script.

You will need to install an extension such as Tampermonkey or Userscripts to install this script.

You will need to install an extension such as Tampermonkey to install this script.

You will need to install a user script manager extension to install this script.

(I already have a user script manager, let me install it!)

You will need to install an extension such as Stylus to install this style.

You will need to install an extension such as Stylus to install this style.

You will need to install an extension such as Stylus to install this style.

You will need to install a user style manager extension to install this style.

You will need to install a user style manager extension to install this style.

You will need to install a user style manager extension to install this style.

(I already have a user style manager, let me install it!)

// ==UserScript==
// @name         mTurk HIT Fullscreen Crosshair CSS (as Userscript)
// @namespace    salembeats
// @version      1.7
// @description  Userscript adapatation (and improvement) of code found at https://codepen.io/michaelsboost/pen/fnizu - applied to mTurk.
// @author       Cuyler Stuwe (salembeats) using code adapted from Michael Schwartz
// @include      *
// @grant        none
// ==/UserScript==

// *****************************************************************************

function isNotMturkFrame() {
	return !(
		window !== window.top &&
		document.referrer.includes("worker.mturk.com/projects/")
	);
}

if(isNotMturkFrame()) {return;}

// *****************************************************************************

// Just here for faster autocomplete suggestions.

const CROSSHAIR_STYLES = {
	DOTTED: "dotted",
	DASHED: "dashed",
	SOLID: "solid"
};

const CROSSHAIR_COLORS = {
	BLACK: "black",
	RED: "red",
	GREEN: "green",
	BLUE: "blue"
};

// *****************************************************************************
// SET UP YOUR CROSSHAIR STYLE HERE.
// *****************************************************************************

const CROSSHAIR_THICKNESS_PX                    = 1;
const CROSSHAIR_STYLE                           = CROSSHAIR_STYLES.DOTTED;
const CROSSHAIR_COLOR                           = CROSSHAIR_COLORS.RED;
const SHOULD_MODIFY_POINTER_TO_CROSSHAIR_CURSOR = true;

// *****************************************************************************

document.body.insertAdjacentHTML("beforeend", `
<div id="crosshair-h" class="hair"></div>
<div id="crosshair-v" class="hair"></div>
`);

document.head.insertAdjacentHTML("beforeend", `
<style>

* {

    ${SHOULD_MODIFY_POINTER_TO_CROSSHAIR_CURSOR ? "cursor: crosshair !important;" : ""}

}

#crosshair-h {

    width: 100%;

}

#crosshair-v {

    height: 100%;

}

.hair {

    position: fixed;
    top:0; left:0;

    margin-top: 0px; /* The offset here by the original author made zero sense. */
    margin-left: 0px; /* The offset here by the original author made zero sense. */

    background: transparent;

    border-top: ${CROSSHAIR_THICKNESS_PX}px ${CROSSHAIR_STYLE} ${CROSSHAIR_COLOR};
    border-left: ${CROSSHAIR_THICKNESS_PX}px ${CROSSHAIR_STYLE} ${CROSSHAIR_COLOR};

    pointer-events: none;

    z-index: ${Number.MAX_SAFE_INTEGER};

}
</style>
`);

let cH = document.getElementById('crosshair-h'),
	cV = document.getElementById('crosshair-v');

document.addEventListener("mousemove", e => {
	cH.style.top  = e.clientY + "px";
	cV.style.left = e.clientX + "px";
});