是的，使用FileAPI，然后您可以使用canvas元素处理图像。
供参考，汇编源代码：
// from an input elementvar filesToUpload = input.files;var file = filesToUpload[0];var img = document.createElement("img");var reader = new FileReader(); reader.onload = function(e) {img.src = e.target.result}reader.readAsDataURL(file);var ctx = canvas.getContext("2d");ctx.drawImage(img, 0, 0);var MAX_WIDTH = 800;var MAX_HEIGHT = 600;var width = img.width;var height = img.height;if (width > height) { if (width > MAX_WIDTH) { height *= MAX_WIDTH / width; width = MAX_WIDTH; }} else { if (height > MAX_HEIGHT) { width *= MAX_HEIGHT / height; height = MAX_HEIGHT; }}canvas.width = width;canvas.height = height;var ctx = canvas.getContext("2d");ctx.drawImage(img, 0, 0, width, height);var dataurl = canvas.toDataURL("image/png");//Post dataurl to the server with AJAX
