JAVASCRIPT

check if element is visible

.is(':visible')
//Selects all elements that are visible.

if($('#Div').is(':visible')){
	// add whatever code you want to run here.
}

$('#yourDiv:visible').callYourFunction();

js check if element hidden

if (elem.getAttribute("hidden") != null){
  //code if elem is hidden
}

check if element is visible or hidden in dom

// Where el is the DOM element you'd like to test for visibility
function isHidden(el) {
    var style = window.getComputedStyle(el);
    return (style.display === 'none')
}

javascript check if visible

window.getComputedStyle(document.getElementById("mydivID"),null).getPropertyValue('display')

check element is visible js

function isVisible(elem) {
    if (!(elem instanceof Element)) throw Error('DomUtil: elem is not an element.');
    const style = getComputedStyle(elem);
    if (style.display === 'none') return false;
    if (style.visibility !== 'visible') return false;
    if (style.opacity < 0.1) return false;
    if (elem.offsetWidth + elem.offsetHeight + elem.getBoundingClientRect().height +
        elem.getBoundingClientRect().width === 0) {
        return false;
    }
    const elemCenter   = {
        x: elem.getBoundingClientRect().left + elem.offsetWidth / 2,
        y: elem.getBoundingClientRect().top + elem.offsetHeight / 2
    };
    if (elemCenter.x < 0) return false;
    if (elemCenter.x > (document.documentElement.clientWidth || window.innerWidth)) return false;
    if (elemCenter.y < 0) return false;
    if (elemCenter.y > (document.documentElement.clientHeight || window.innerHeight)) return false;
    let pointContainer = document.elementFromPoint(elemCenter.x, elemCenter.y);
    do {
        if (pointContainer === elem) return true;
    } while (pointContainer = pointContainer.parentNode);
    return false;
}