The Window.screenLeft
read-only property returns the horizontal distance, in CSS pixels, from the left border of the user's browser viewport to the left side of the screen.
Note: screenLeft
is an alias of the older Window.screenX
property. screenLeft
was originally supported only in IE but was introduced everywhere due to popularity.
Syntax
leftWindowPos = window.screenLeft
Returns
A number equal to the number of CSS pixels from the left edge of the browser viewport to the left edge of the screen.
Examples
In our [[../../../../../../../mdn.github.io/dom-examples/screenleft-screentop/index|screenleft-screentop]] example, you'll see a canvas onto which has been drawn a circle. In this example we are using screenLeft
/screenTop
plus Window.requestAnimationFrame()
to constantly redraw the circle in the same physical position on the screen, even if the window position is moved.
initialLeft = window.screenLeft + canvasElem.offsetLeft;
initialTop = window.screenTop + canvasElem.offsetTop;
function positionElem() {
let newLeft = window.screenLeft + canvasElem.offsetLeft;
let newTop = window.screenTop + canvasElem.offsetTop;
let leftUpdate = initialLeft - newLeft;
let topUpdate = initialTop - newTop;
ctx.fillStyle = 'rgb(0, 0, 0)';
ctx.fillRect(0, 0, width, height);
ctx.fillStyle = 'rgb(0, 0, 255)';
ctx.beginPath();
ctx.arc(leftUpdate + (width/2), topUpdate + (height/2) + 35, 50, degToRad(0), degToRad(360), false);
ctx.fill();
pElem.textContent = 'Window.screenLeft: ' + window.screenLeft + ', Window.screenTop: ' + window.screenTop;
window.requestAnimationFrame(positionElem);
}
window.requestAnimationFrame(positionElem);
Also in the code we include a snippet that detects whether screenLeft
is supported, and if not, polyfills in screenLeft
/screenTop
using Window.screenX
/Window.screenY
.
if(!window.screenLeft) {
window.screenLeft = window.screenX;
window.screenTop = window.screenY;
}
Specifications
Specification | Status | Comment |
---|---|---|
CSS Object Model (CSSOM) View ModuleThe definition of 'Window.screenLeft' in that specification. | Working Draft | Initial definition. |
Browser compatibility
The compatibility table on this page is generated from structured data. If you'd like to contribute to the data, please check out https://github.com/mdn/browser-compat-data and send us a pull request.
Update compatibility data on GitHub
Desktop | Mobile | |||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|
screenLeft
|
Chrome
Full support 1 |
Edge
Full support 12 |
Firefox
Full support 64 |
IE
Full support 5 |
Opera
Full support ≤12.1 |
Safari
Full support 1 |
WebView Android
Full support 1 |
Chrome Android
Full support 18 |
Firefox Android
Full support 64 |
Opera Android
Full support ≤12.1 |
Safari iOS
Full support 1 |
Samsung Internet Android
Full support 1.0 |
Legend
- Full support
- Full support
See also
Window.screenLeft by Mozilla Contributors is licensed under CC-BY-SA 2.5.