Gmail API - Parse message content (Base64 decoding?) with Javascript

Question

I\'m trying to use the Gmail API to get a user\'s email, grab the message subject and body, and then display it on a webpage. I\'ll be doing other stuff with it, but this is

Answer 1

Regarding the Base64 decoding, you can use

atob(dataToDecode)

For Gmail, you'll also want to replace some characters:

atob( dataToDecode.replace(/-/g, '+').replace(/_/g, '/') ); 

The above function is available to you in JavaScript (see ref). I use it myself to decode the Gmail messages. No need to install extra stuff. As an interesting tangent, if you want to encode your message to Base64, use btoa.

Now, for accessing your message payload, you can write a function:

var extractField = function(json, fieldName) {
  return json.payload.headers.filter(function(header) {
    return header.name === fieldName;
  })[0].value;
};
var date = extractField(response, "Date");
var subject = extractField(response, "Subject");

referenced from my previous SO Question and

var part = message.parts.filter(function(part) {
  return part.mimeType == 'text/html';
});
var html = atob(part.body.data.replace(/-/g, '+').replace(/_/g, '/'));