js文件下载

1.文件流下载

根据后台接口文件流下载

// ts文件
export function downloadByData(data: BlobPart, filename: string, mime?: string, bom?: BlobPart) {
  const blobData = typeof bom !== 'undefined' ? [bom, data] : [data];
  const blob = new Blob(blobData, { type: mime || 'application/octet-stream' });
  if (typeof window.navigator.msSaveBlob !== 'undefined') {
    window.navigator.msSaveBlob(blob, filename);
  } else {
    const blobURL = window.URL.createObjectURL(blob);
    const tempLink = document.createElement('a');
    tempLink.style.display = 'none';
    tempLink.href = blobURL;
    tempLink.setAttribute('download', filename);
    if (typeof tempLink.download === 'undefined') {
      tempLink.setAttribute('target', '_blank');
    }
    document.body.appendChild(tempLink);
    tempLink.click();
    document.body.removeChild(tempLink);
    window.URL.revokeObjectURL(blobURL);
  }
}

调用

downloadByData('text content', 'testName.txt');

2.文件地址下载

根据文件地址下载文件

export function openWindow(url, opt) {
  const { target = '__blank', noopener = true, noreferrer = true } = opt || {};
  const feature = [];
  noopener && feature.push('noopener=yes');
  noreferrer && feature.push('noreferrer=yes');
  window.open(url, target, feature.join(','));
}
export function downloadByUrl({
  url,
  target = '_blank',
  fileName,
}) {
  const isChrome = window.navigator.userAgent.toLowerCase().indexOf('chrome') > -1;
  const isSafari = window.navigator.userAgent.toLowerCase().indexOf('safari') > -1;

  if (/(iP)/g.test(window.navigator.userAgent)) {
    console.error('Your browser does not support download!');
    return false;
  }
  if (isChrome || isSafari) {
    const link = document.createElement('a');
    link.href = url;
    link.target = target;

    if (link.download !== undefined) {
      link.download = fileName || url.substring(url.lastIndexOf('/') + 1, url.length);
    }

    if (document.createEvent) {
      const e = document.createEvent('MouseEvents');
      e.initEvent('click', true, true);
      link.dispatchEvent(e);
      return true;
    }
  }
  if (url.indexOf('?') === -1) {
    url += '?download';
  }

  openWindow(url, { target });
  return true;
}

调用

 downloadByUrl({
          url: 'https://vebn.oss-cn-beijing.aliyuncs.com/vben/logo.png',
          target: '_self',
        });

3.base64流下载

base64流下载

export function downloadByBase64(buf: string, filename: string, mime?: string, bom?: BlobPart) {
  const base64Buf = dataURLtoBlob(buf);
  downloadByData(base64Buf, filename, mime, bom);
}
export function downloadByData(data: BlobPart, filename: string, mime?: string, bom?: BlobPart) {
  const blobData = typeof bom !== 'undefined' ? [bom, data] : [data];
  const blob = new Blob(blobData, { type: mime || 'application/octet-stream' });
  if (typeof window.navigator.msSaveBlob !== 'undefined') {
    window.navigator.msSaveBlob(blob, filename);
  } else {
    const blobURL = window.URL.createObjectURL(blob);
    const tempLink = document.createElement('a');
    tempLink.style.display = 'none';
    tempLink.href = blobURL;
    tempLink.setAttribute('download', filename);
    if (typeof tempLink.download === 'undefined') {
      tempLink.setAttribute('target', '_blank');
    }
    document.body.appendChild(tempLink);
    tempLink.click();
    document.body.removeChild(tempLink);
    window.URL.revokeObjectURL(blobURL);
  }
}

调用

downloadByBase64(imgBase64, 'logo.png');

4.图片Url下载

图片Url下载,如果有跨域问题，需要处理图片跨域

export function urlToBase64(url: string, mineType?: string): Promise<string> {
  return new Promise((resolve, reject) => {
    let canvas = document.createElement('CANVAS') as Nullable<HTMLCanvasElement>;
    const ctx = canvas!.getContext('2d');

    const img = new Image();
    img.crossOrigin = '';
    img.onload = function () {
      if (!canvas || !ctx) {
        return reject();
      }
      canvas.height = img.height;
      canvas.width = img.width;
      ctx.drawImage(img, 0, 0);
      const dataURL = canvas.toDataURL(mineType || 'image/png');
      canvas = null;
      resolve(dataURL);
    };
    img.src = url;
  });
}

export function downloadByOnlineUrl(url: string, filename: string, mime?: string, bom?: BlobPart) {
  urlToBase64(url).then((base64) => {
    downloadByBase64(base64, filename, mime, bom);
  });
}
export function downloadByBase64(buf: string, filename: string, mime?: string, bom?: BlobPart) {
  const base64Buf = dataURLtoBlob(buf);
  downloadByData(base64Buf, filename, mime, bom);
}

调用

downloadByOnlineUrl(
          'https://p3-juejin.byteimg.com/tos-cn-i-k3u1fbpfcp/5944817f47b8408e9f1442ece49d68ca~tplv-k3u1fbpfcp-watermark.image',
          'logo.png'
        );