Javascript的base64实现及使用

实例及实现原理如下

var uploadKey = 'avatar/20191212/userid-1.png';

// key 进行base64处理
// 第一步使用encodeURIComponent() 函数把字符串作为 URI 组件进行编码
// 第二步使用unescape() 函数对通过 escape() 编码的字符串进行解码
// 第三步使用btoa() 方法用于创建一个 base-64 编码的字符串。该方法使用 "A-Z", "a-z", "0-9", "+", "/" 和 "=" 字符来编码字符串。base64 解码使用方法是 atob() 。

var key = btoa(unescape(encodeURIComponent(uploadKey)));

var url = "http://upload.qiniup.com/putb64/12" + '/key/' + key;

运行上面代码结果如下

> var uploadKey = 'avatar/20191212/userid-1.png';
< undefined
> var key = btoa(unescape(encodeURIComponent(uploadKey)));
< undefined
> var url = "http://upload.qiniup.com/putb64/12"+'/key/'+key; 
< undefined
> console.log(url)
  VM7861:1 http://upload.qiniup.com/putb64/12/key/YXZhdGFyLzIwMTkxMjEyL3VzZXJpZC0xLnBuZw==
> undefined

参考如下 https://stackoverflow.com/questions/246801/how-can-you-encode-a-string-to-base64-in-javascript

我们分解执行下

> var a = encodeURIComponent(uploadKey)
< undefined
> console.log(a)
< avatar%2F20191212%2Fuserid-1.png
> undefined
< var b = unescape(a);
> undefined
< console.log(b)
  avatar/20191212/userid-1.png
> undefined
< var c = btoa(b)
> undefined
< console.log(c)
  YXZhdGFyLzIwMTkxMjEyL3VzZXJpZC0xLnBuZw==
> undefined