Javascript 如何判断字符串是否为'；正确地'；编码到Base64？

我正在尝试将SVG字符串编码为Base64，以便通过AJAX调用将其作为附件发送给电子邮件提供商（我使用的是我的电子邮件提供商）：

出于某种原因，它出现了错误（例如，Gmail显示的SVG图像很好，但当我收到它时，Gmail表示该文件是空的或已损坏）

我无法知道原因。（基本上，如果没有任何关于什么是错误的指导，我无法调试任何东西）

如何检查我的字符串是否以Base64格式正确编码，以及 解码后将生成原始SVG图形

目前，我使用

window.btoa

和

escape

进行编码，这表明了这一点

这是我用于编码的代码：

base64SVG= window.btoa(encodeURIComponent(escape(svgString)));
console.log(base64SVG);

<svg width="580" height="400" xmlns="http://www.w3.org/2000/svg">
 <!-- Created with Ada-BlueDraw - http://github.com/dynamoRtc/Ada-BlueDraw/ -->
 <g>
  <title>background</title>
  <rect fill="#fff" id="canvas_background" stroke="#000" stroke-width="5px" height="402" width="582" y="-1" x="-1"/>
  <g display="none" overflow="visible" y="0" x="0" height="100%" width="100%" id="canvasGrid">
   <rect fill="url(#gridpattern)" stroke-width="0" y="0" x="0" height="100%" width="100%"/>
  </g>
 </g>
 <g>
  <title>Layer 1</title>
  <rect id="svg_1" height="50" width="85" y="145" x="138.5" stroke="#4880FF" fill="#4880FF"/>
  <rect id="svg_2" height="159" width="193" y="89" x="177.5" stroke="#4880FF" fill="#4880FF"/>
 </g>
</svg> 

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这是我的“输入”SVG字符串：

base64SVG= window.btoa(encodeURIComponent(escape(svgString)));
console.log(base64SVG);

<svg width="580" height="400" xmlns="http://www.w3.org/2000/svg">
 <!-- Created with Ada-BlueDraw - http://github.com/dynamoRtc/Ada-BlueDraw/ -->
 <g>
  <title>background</title>
  <rect fill="#fff" id="canvas_background" stroke="#000" stroke-width="5px" height="402" width="582" y="-1" x="-1"/>
  <g display="none" overflow="visible" y="0" x="0" height="100%" width="100%" id="canvasGrid">
   <rect fill="url(#gridpattern)" stroke-width="0" y="0" x="0" height="100%" width="100%"/>
  </g>
 </g>
 <g>
  <title>Layer 1</title>
  <rect id="svg_1" height="50" width="85" y="145" x="138.5" stroke="#4880FF" fill="#4880FF"/>
  <rect id="svg_2" height="159" width="193" y="89" x="177.5" stroke="#4880FF" fill="#4880FF"/>
 </g>
</svg> 

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根据，附件元素的

内容

属性

附件的内容为base64编码字符串

---

似乎没有任何使用URI编码的要求；只需直接在要用作附件内容的字符串上调用

btoa

。不要使用

escape

或

encodeURIComponent

MDN建议使用

escape

的原因是对字符值大于

255

的字符进行编码。这是因为

btoa

将二进制值转换为文本字符

btoa

假设输入中的一个字符表示二进制输入的一个字节。这并不总是正确的，在这些情况下，

btoa

会抛出一个错误

在一个字符需要多个字节的情况下，编码和解码机制必须就如何关联字节和字符达成一致。MDN建议通过

转义

来消除大于一个字节的字符，然后在解码时使用

unescape

重新组合字符

---

然而，Mandrill在解码时不会这样做。他们可能会做一些不同的事情，将多字节字符映射到多字节二进制输入，或者他们可能根本不支持它。

是的，这里是：

escape

或

encodeURIComponent

需要mandrillapp来解码它们，否则在

文本中会出现大量的%xy。base64字符串看起来不错。@NicholasKyriakides编辑了一些关于base64编码大于一个字节字符的更复杂问题的思考。一个字符怎么可能需要超过一个字节？我认为所有ASCII字符都相当于8位=1字节。这是我上大学时的CS 101。@NicholasKyriakides“一个字符怎么可能需要超过一个字节？”你是说所有可打印字符都可以映射到字节值上吗？从这里，我们可以得出结论，您的计算机只能在文本中表达256个字符！对此，我只能说：“码码>上的2010 2010方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方图6 6月月月月月月月月月月月月月月月月月月月月月月月月月月月月月月月月月月月月月月月月月月月月月月月月月月月月月月月月月月月月月月月月月月月月月月月月月月月月月月月月月月月月月月月月月月月月月月月月月月月月月月月月月月月月月月月月月月月月月月月月月月月月月月月月月月月月月月月月月月月月月月月月月月月月月月月月月月月月月月月月月月月月月月月月月月月月月月月的的的的的的的的图图图图图图图图图图图图图图图图图图图图图图图图图图图图图图图图图图图图图图图图图图图图图图图图图图图图图图图ѯ本1177月日日日日日日日日日日日日日日日日日方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方方嗯，也许我没有注意CS101。@NicholasKyriakides进一步解释：ASCII是7位编码范围（“扩展ASCII”是8位范围）。ASCII不再被广泛使用；不过，它作为一种记住UTF-8 unicode值的方法很有用，因为UTF-8的前128个代码点与ASCII值相同。（：“UTF-8对Unicode代码空间中的1112064个有效代码点进行编码”。）文本编码非常复杂，我不知道如何进一步解释它，只能说它非常非常深入。