const file = event.target.files[0];
const img = new Image();
img.onload = function () {
  width = img.width;
  height = img.height;
};
img.src = URL.createObjectURL(file);
alert(width + "x" + height);

您可以通过编程方式获取图像并使用JavaScript检查尺寸…

const img = new Image(); img。Onload = function() { 警报(这。Width + 'x' + this.height); ｝ img。src = 'http://www.google.com/intl/en_ALL/images/logo.gif';

如果图像不是标记的一部分，这可能很有用。

你还可以使用:

var image=document.getElementById("imageID");
var width=image.offsetWidth;
var height=image.offsetHeight;

假设，我们想要得到<img id="an-img" src"…" >

// Query after all the elements on the page have loaded.
// Or, use `onload` on a particular element to check if it is loaded.
document.addEventListener('DOMContentLoaded', function () {
  var el = document.getElementById("an-img");

  console.log({
    "naturalWidth": el.naturalWidth, // Only on HTMLImageElement
    "naturalHeight": el.naturalHeight, // Only on HTMLImageElement
    "offsetWidth": el.offsetWidth,
    "offsetHeight": el.offsetHeight
  });
})

自然维度

埃尔。naturalWidth和el。naturalHeight会得到图像文件的自然尺寸。

布局尺寸

埃尔。offsetWidth和el。offsetHeight将为我们提供元素在文档上呈现的尺寸。

让我们将在这里学到的所有内容组合成一个简单的函数(imageDimensions())。它使用承诺。

// helper to get dimensions of an image const imageDimensions = file => new Promise((resolve, reject) => { const img = new Image() // the following handler will fire after a successful loading of the image img.onload = () => { const { naturalWidth: width, naturalHeight: height } = img resolve({ width, height }) } // and this handler will fire if there was an error with the image (like if it's not really an image or a corrupted one) img.onerror = () => { reject('There was some problem with the image.') } img.src = URL.createObjectURL(file) }) // here's how to use the helper const getInfo = async ({ target: { files } }) => { const [file] = files try { const dimensions = await imageDimensions(file) console.info(dimensions) } catch(error) { console.error(error) } } <script src="https://cdnjs.cloudflare.com/ajax/libs/babel-standalone/7.0.0-beta.3/babel.min.js"></script> Select an image: <input type="file" onchange="getInfo(event)" /> <br /> <small>It works offline.</small>

如果你正在使用jQuery并且你正在请求图像大小，你必须等待它们加载，否则你只会得到零。

$(document).ready(function() {
    $("img").load(function() {
        alert($(this).height());
        alert($(this).width());
    });
});