笔记-btoa atob

btoa和atob是window对象的两个函数，

btoa -- binary to ascii，用于将binary的数据用ascii码表示，即Base64的编码过程，

atob -- ascii to binary，用于将ascii码解析成binary数据

 

不支持汉字

先用encodeURIComponent编码

var string = "Hello, 中国！";
//"SGVsbG8lMkMlMjAlRTQlQjglQUQlRTUlOUIlQkQlRUYlQkMlODE="
var encodedString = btoa(encodeURIComponent(string));
var decodedString = decodeURIComponent(atob(encodedString));
console.log(decodedString); //"Hello, 中国！"

 

IE9 以下下是不支持的atob

兼容ie

// Create Base64 Object
    var Base64 = {
      _keyStr: "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/=",
      encode: function (e) {
        var t = ""; var n, r, i, s, o, u, a;
        var f = 0;
        e = Base64._utf8_encode(e);
        while (f < e.length) {
          n = e.charCodeAt(f++);
          r = e.charCodeAt(f++);
          i = e.charCodeAt(f++);
          s = n >> 2;
          o = (n & 3) << 4 | r >> 4;
          u = (r & 15) << 2 | i >> 6;
          a = i & 63;
          if (isNaN(r)) {
            u = a = 64
          } else if (isNaN(i)) {
            a = 64
          }
          t = t + this._keyStr.charAt(s) + this._keyStr.charAt(o) + this._keyStr.charAt(u) + this._keyStr.charAt(a)
        }
        return t
      },
      decode: function (e) {
        var t = "";
        var n, r, i;
        var s, o, u, a;
        var f = 0;
        e = e.replace(/[^A-Za-z0-9+/=]/g, "");
        while (f < e.length) {
          s = this._keyStr.indexOf(e.charAt(f++));
          o = this._keyStr.indexOf(e.charAt(f++));
          u = this._keyStr.indexOf(e.charAt(f++));
          a = this._keyStr.indexOf(e.charAt(f++));
          n = s << 2 | o >> 4;
          r = (o & 15) << 4 | u >> 2;
          i = (u & 3) << 6 | a;
          t = t + String.fromCharCode(n);
          if (u != 64) {
            t = t + String.fromCharCode(r)
          }
          if (a != 64) {
            t = t + String.fromCharCode(i)
          }
        }
        t = Base64._utf8_decode(t);
        return t
      },
      _utf8_encode: function (e) {
        e = e.replace(/rn/g, "n");
        var t = "";
        for (var n = 0; n < e.length; n++) {
          var r = e.charCodeAt(n);
          if (r < 128) {
            t += String.fromCharCode(r)
          } else if (r > 127 && r < 2048) {
            t += String.fromCharCode(r >> 6 | 192);
            t += String.fromCharCode(r & 63 | 128)
          } else {
            t += String.fromCharCode(r >> 12 | 224);
            t += String.fromCharCode(r >> 6 & 63 | 128);
            t += String.fromCharCode(r & 63 | 128)
          }
        }
        return t
      },
      _utf8_decode: function (e) {
        var t = "";
        var n = 0; var r = c1 = c2 = 0;
        while (n < e.length) {
          r = e.charCodeAt(n);
          if (r < 128) {
            t += String.fromCharCode(r);
            n++
          } else if (r > 191 && r < 224) {
            c2 = e.charCodeAt(n + 1);
            t += String.fromCharCode((r & 31) << 6 | c2 & 63);
            n += 2
          } else {
            c2 = e.charCodeAt(n + 1);
            c3 = e.charCodeAt(n + 2);
            t += String.fromCharCode((r & 15) << 12 | (c2 & 63) << 6 | c3 & 63);
            n += 3
          }
        }
        return t
      }
    }

    // Define the string
    var string = 'Hello World!';

    // Encode the String
    var encodedString = Base64.encode(string);
    console.log(encodedString); // Outputs: "SGVsbG8gV29ybGQh"

    // Decode the String
    var decodedString = Base64.decode(encodedString);
    console.log(decodedString); // Outputs: "Hello World!"