如何将图像转换为 base64 React Native

Question

您能否建议我使用任何库或其他方法将此图像转换为 base64 的最佳方法：

第一次以为属性data是base64，但是我用了这个函数：

function isBase64(str) {
if (str ==='' || str.trim() ===''){ return false; }
try {
    return btoa(atob(str)) == str;
} catch (err) {
    return false;
}}

所以，当我介绍这个 function 的属性data时，我返回false

Answer 1

如果你愿意的话。 您可以复制以下代码，并使用这些方法。

const chars =
  'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/=';

const Base64 = {
  btoa: (input = '') => {
    let str = input;
    let output = '';

    for (
      let block = 0, charCode, i = 0, map = chars;
      str.charAt(i | 0) || ((map = '='), i % 1);
      output += map.charAt(63 & (block >> (8 - (i % 1) * 8)))
    ) {
      charCode = str.charCodeAt((i += 3 / 4));

      if (charCode > 0xff) {
        throw new Error(
          "'btoa' failed: The string to be encoded contains characters outside of the Latin1 range.",
        );
      }

      block = (block << 8) | charCode;
    }

    return output;
  },

  atob: (input = '') => {
    let str = input.replace(/[=]+$/, '');
    let output = '';

    if (str.length % 4 == 1) {
      throw new Error(
        "'atob' failed: The string to be decoded is not correctly encoded.",
      );
    }
    for (
      let bc = 0, bs = 0, buffer, i = 0;
      (buffer = str.charAt(i++));
      ~buffer && ((bs = bc % 4 ? bs * 64 + buffer : buffer), bc++ % 4)
        ? (output += String.fromCharCode(255 & (bs >> ((-2 * bc) & 6))))
        : 0
    ) {
      buffer = chars.indexOf(buffer);
    }

    return output;
  },
};

export default Base64;