node base64类型转换

base64字符串 to File

  const matchreg = srcBase64.match(/^data:image\/(\w+);base64,(.*)/);
  if (!matchreg || matchreg.length !== 3) return null;
  const [, mime, base64] = matchreg;
  const bstr = atob(base64);
  let n = bstr.length;
  const u8arr = new Uint8Array(n);
  while (n--) {
    u8arr[n] = bstr.charCodeAt(n);
  }
  const rs = new File([u8arr], `clipboard.${mime}`, { type: `image/${mime}` });

base64字符串 to Blob

上述代码最后一行改为

  const rs = new Blob([u8arr], { type: `image/${mime}` });

base64字符串 to "ascii" | "utf8" | "utf-8" | "utf16le" | "ucs2" | "ucs-2" | "base64" | "latin1" | "binary" | "hex"

上述代码最后一行改为

    const base64 = insert.image.replace(/^data:image\/\w+;base64,/, '');
    const buf = new Buffer(base64, 'base64');
    return buf.toString('binary')

base64字符串 保存为文件

    const matchreg = srcBase64.match(/^data:image\/(\w+);base64,(.*)/);
    if (!matchreg || matchreg.length !== 3) return null;
    const [, mime, base64] = matchreg;
    const buffer = Buffer.from(base64Data, 'base64');
    fs.writeFileSync(`/usr/ttt.${mime}`, buffer)

图片url转base64字符串

const img = new Image();
img.src = url;
img.onload = () => {
    const c = document.createElement('canvas') as HTMLCanvasElement;
    c.width = width || img.naturalWidth;
    c.width = c.width > 500 ? 500 : c.width;
    c.height = (img.naturalHeight * c.width) / img.naturalWidth;
    const cxt = c.getContext('2d') as CanvasRenderingContext2D;
    cxt.drawImage(img, 0, 0, img.naturalWidth, img.naturalHeight, 0, 0, c.width, c.height);
    resolve(c.toDataURL('image/jpg'));
};

跨域图片url转base64字符串

function img2base64(url: string): Promise<string> {
  return new Promise((resolve) => {
    if (url.includes('data:image/')) {
      resolve(url);
      return;
    }
    const request = url.startsWith('https') ? httpsGet : httpGet;
    request(url, (res) => {
      // eslint-disable-next-line @typescript-eslint/no-explicit-any
      const chunks: any = [];
      let size = 0;
      res.on('data', (chunk) => {
        chunks.push(chunk);
        size += chunk.length;
      });
      res.on('end', () => {
        const data = Buffer.concat(chunks, size);
        const base64 = data.toString('base64');
        const ext = url.lastIndexOf('.') ? url.substr(url.lastIndexOf('.')) : 'jpg';
        resolve(`data:image/${ext};base64,${base64}`);
      });
    });
  });
}