javascript - 预加载图库图像。 JavaScript(无 JQuery)

Question

我正在尝试在画廊中使用一些大文件大小的图像。我正在尝试以最简单的方式做到这一点。这里我仅使用一些示例图像:

var imageGallery = ["nebula.jpg", "galaxy.jpg", "blackHole.jpg"];

for (var i = 0; i < imageGallery.length - 1; i++) {
    var img = new Image();
    img.src = imageGallery[i];
}

我知道这段代码将确保图像在被脚本的其余部分使用之前被缓存，但它不起作用。

如果有帮助，我们将不胜感激。

Answer 1

您正在寻找某种异步回调，您必须执行以下操作:

// Grab reference to image on page
var img = document.getElementById("blah");  // Or whatever you need to do

// Create new image from your list
var galleryImage = new Image();

// Create a callback that will start once you assign the src attribute to img 
galleryImage.onload = function() {

    // Here you could disable a loading icon or something, because your image is ready to go
    img.src = this.src;
}

// Kickoff everything
galleryImage.src = "www.myimage.com/path";

<小时/>

在您的代码中可能看起来像这样:

var imageGallery = ["nebula.jpg", "galaxy.jpg", "blackHole.jpg"];

for (var i = 0; i < imageGallery.length - 1; i++) {
    var img = document.document.getElementsByTagName('img')[i];
    var galleryImage = new Image();

    galleryImage.onload = function() {
        img.src = this.src;
    }

    galleryImage.src = imageGallery[i];
}