bookmarklet-ruler.js

javascript: void((function(){
    var rulers = document.getElementsByClassName('js-pro.logvinenko.js.ruler');
    if (rulers.length > 0) {
        document.removeEventListener('mousemove', moveRuler);
        var ruler = rulers[0];
        document.body.style.cursor = ruler.getAttribute('data-cursor');
        document.body.removeChild(ruler);
        ruler = null;
    } else {
        var ruler = document.createElement('div');
        ruler.className = 'js-pro.logvinenko.js.ruler';
        ruler.setAttribute('data-cursor', document.body.style.cursor);

        ruler.style.border = '.5px solid rgba(255, 0, 0, .5)';
        ruler.style.boxSizing = 'border-box';
        ruler.style.display = 'block';
        ruler.style.height = '0px';
        ruler.style.left = '0';
        ruler.style.top = '0';
        ruler.style.position = 'fixed';
        ruler.style.width = '100vw';
        ruler.style.zIndex = '9999';
        
        document.body.style.cursor='row-resize';
        document.body.appendChild(ruler);
        document.addEventListener('mousemove', moveRuler);
    }

    function moveRuler(e) {
        ruler.style.top = e.clientY + 'px';
    }
})());