//url下载图片路径  filename自定义文件名字
	function download(url, filename) {

		getBlob(url, function (blob) {
			saveAs(blob, filename);
		});

	};

	function getBlob(url, cb) {
		var xhr = new XMLHttpRequest();
		xhr.open('GET', url, true);
		xhr.responseType = 'blob';
		xhr.onload = function () {
			if (xhr.status === 200) {
				cb(xhr.response);
			}
		};
		xhr.send();
	}

	function saveAs(blob, filename) {
		if (window.navigator.msSaveOrOpenBlob) {
			navigator.msSaveBlob(blob, filename);
		} else {
			var link = document.createElement('a');
			var body = document.querySelector('body');
			link.href = window.URL.createObjectURL(blob);
			link.download = filename;
			// fix Firefox
			link.style.display = 'none';
			body.appendChild(link);
			link.click();
			body.removeChild(link);
			window.URL.revokeObjectURL(link.href);
		};

	}