Image native width in jquery

With jQuery, i change the src of an image on click

$("#thumb li img").click(function() {
var n开发者_JS百科ewlinkimage = $(this).attr("src");

newlinkimage = newlinkimage.substring(14,17);

    $("#avant img").attr("src", 'retouche-hr' + newlinkimage + '-a.jpg');
    $("#apres img").attr("src", 'retouche-hr' +newlinkimage + '-b.jpg');

The problem is, that the NEW image width is different that the old. HOW do i get the NATIVE width of the new image (like the little arrow that get that in dreamweaver

This is the plain javascript way to do it. It should be easy to integrate this into your code.

var newimage = new Image();
newimage.src = 'retouche-hr' + newlinkimage + '-a.jpg'; // path to image
var width = newimage.width;
var height = newimage.height;

Did the old image have a width and height set to it? If you use $(image).width("") it should reset the width back to what it was before you applied any width changes to it (similarly for height). I don't think this will work for images that had their width set via CSS or the property though. After you reset to the old width, you can use .outerWidth() to get the width of the image.

You want to get the real width of the image before changing it, then set the new picture to that width. you can do this with $(img).load:

var pic_real_width;
var pic_real_height;

$(img).load(function() {
    // need to remove these in of case img-element has set width and height
    $(this).removeAttr("width")
           .removeAttr("height");

    pic_real_width = this.width;
    pic_real_height = this.height;
});

$("#thumb li img").click(function() {
var newlinkimage = $(this).attr("src");

newlinkimage = newlinkimage.substring(14,17);

        $("#avant img").attr("src", 'retouche-hr' + newlinkimage + '-a.jpg').width(pic_real_width);
        $("#apres img").attr("src", 'retouche-hr' +newlinkimage + '-b.jpg').width(pic_real_width);

this code always return Zero '0'

    var newimage = new Image();
    newimage.src = 'retouche-hr' + newlinkimage.substring(14,17) + '-a.jpg'; 
    var width = newimage.naturalWidth;
    var height = newimage.naturalHeight;
    alert (width);

WHY ???