Denny_KK Posted February 4, 2021 Share Posted February 4, 2021 I am confusing the first line of code in red " dragElement(document.getElementById("mydiv")); ". What do it mean? Is there any other way to do it ? Thank you --------------------------------------- original link of the code: https://www.w3schools.com/howto/tryit.asp?filename=tryhow_js_draggable <script> //Make the DIV element draggagle:dragElement(document.getElementById("mydiv")); function dragElement(elmnt) { var pos1 = 0, pos2 = 0, pos3 = 0, pos4 = 0; if (document.getElementById(elmnt.id + "header")) { /* if present, the header is where you move the DIV from:*/ document.getElementById(elmnt.id + "header").onmousedown = dragMouseDown; } else { /* otherwise, move the DIV from anywhere inside the DIV:*/ elmnt.onmousedown = dragMouseDown; } function dragMouseDown(e) { e = e || window.event; e.preventDefault(); // get the mouse cursor position at startup: pos3 = e.clientX; pos4 = e.clientY; document.onmouseup = closeDragElement; // call a function whenever the cursor moves: document.onmousemove = elementDrag; } function elementDrag(e) { e = e || window.event; e.preventDefault(); // calculate the new cursor position: pos1 = pos3 - e.clientX; pos2 = pos4 - e.clientY; pos3 = e.clientX; pos4 = e.clientY; // set the element's new position: elmnt.style.top = (elmnt.offsetTop - pos2) + "px"; elmnt.style.left = (elmnt.offsetLeft - pos1) + "px"; } function closeDragElement() { /* stop moving when mouse button is released:*/ document.onmouseup = null; document.onmousemove = null; } } </script> Link to comment Share on other sites More sharing options...
Ingolme Posted February 4, 2021 Share Posted February 4, 2021 I'm not sure what you're looking for. There may be other ways to access the element, but you still need to pass a reference to the element to the dragElement() function. The line of code can be broken down into two parts: document.getElementById("mydiv"); gets a reference to the element. Read more about getElementById() here: https://www.w3schools.com/jsref/met_document_getelementbyid.asp dragElement( ... ) is the function defined right below. It takes an HTML element as a parameter. You can read about function parameters here: https://www.w3schools.com/js/js_functions.asp Link to comment Share on other sites More sharing options...
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