JS实现图片URL转Base64：跨域处理与Node.js中间层方案

const image2Base64 = (url: string) => new Promise((resolve, reject) => {
  if (!url) {
    resolve('');
    return;
  }
  const img = new Image();
  img.crossOrigin = 'anonymous';
  img.src = url;
  img.onload = () => {
    const canvas = document.createElement('canvas');
    canvas.width = img.width;
    canvas.height = img.height;
    const ctx = canvas.getContext('2d');
    ctx?.drawImage(img, 0, 0);
    const data = canvas.toDataURL();
    resolve(data);
  };
  img.onerror = () => {
    reject('');
  };
});

const http = require('http');
http.get(url, (res) => {
  const chunks = [];
  let size = 0;
  res.on('data', (chunk) => {
    chunks.push(chunk);
    size += chunk.length;
  });
  res.on('end', () => {
    const data = Buffer.concat(chunks, size);
    const base64Data = data.toString('base64');
    return base64Data;
  });
});