HTMLElement.offsetLeft

The HTMLElement.offsetLeft read-only property returns the number of pixels that the upper left corner of the current element is offset to the left within the HTMLElement.offsetParent node.

For block-level elements, offsetTop, offsetLeft, offsetWidth, and offsetHeight describe the border box of an element relative to the offsetParent.

However, for inline-level elements (such as span) that can wrap from one line to the next, offsetTop and offsetLeft describe the positions of the first border box (use Element.getClientRects() to get its width and height), while offsetWidth and offsetHeight describe the dimensions of the bounding border box (use Element.getBoundingClientRect() to get its position). Therefore, a box with the left, top, width and height of offsetLeft, offsetTop, offsetWidth and offsetHeight will not be a bounding box for a span with wrapped text.

An integer.

var colorTable = document.getElementById("t1");
var tOLeft = colorTable.offsetLeft;

if (tOLeft > 5) {
  // large left offset: do something here
}

This example shows a 'long' sentence that wraps within a div with a blue border, and a red box that one might think should describe the boundaries of the span.

<div style="width: 300px; border-color:blue; border-style:solid; border-width:1;">
  <span>Short span. </span>
  <span id="longspan">Long span that wraps within this div.</span>
</div>

<div id="box" style="position: absolute; border-color: red; border-width: 1; border-style: solid; z-index: 10">
</div>

<script type="text/javascript">
  var box = document.getElementById("box");
  var longspan = document.getElementById("longspan");
  box.style.left = longspan.offsetLeft + document.body.scrollLeft + "px";
  box.style.top = longspan.offsetTop + document.body.scrollTop + "px";
  box.style.width = longspan.offsetWidth + "px";
  box.style.height = longspan.offsetHeight + "px";
</script>

• HTMLElement.offsetParent, HTMLElement.offsetTop, HTMLElement.offsetWidth, HTMLElement.offsetHeight