GetAccessTokenFromServiceAccount_js

Overview

This is a Javascript library to retrieve the access token from the Google Service Account. Ref

Description

I have already posted the sample script for retrieving the access token from the Google Service Account. Ref But, when I use this script, I thought that when this was published as the Javascript library, it will be useful. So I created this.

Install

<script src="getaccesstokengromserviceaccount_js.min.js"></script>

Or, using jsdelivr cdn

<script src="https://cdn.jsdelivr.net/gh/tanaikech/GetAccessTokenFromServiceAccount_js@master/getaccesstokengromserviceaccount_js.min.js"></script>

Method

Method	Explanation
do(object)	Retrieve the access token from the service account

Usage

Sample script

When the API key is used, the values can be retrieved from only the publicly shared folder. Please be careful this. If you want to retrieve the folder which is not shared in your Google Drive, please use the access token.

<script src="getfilelist_js.min.js"></script>

<script>
  const obj = {
    private_key: "-----BEGIN PRIVATE KEY-----\n###-----END PRIVATE KEY-----\n",
    client_email: "###",
    scopes: ["https://www.googleapis.com/auth/drive.readonly"],
    // userEmail: "###",
  };
  const p = GetAccessTokenFromServiceAccount.do(obj)
    .then((res) => console.log(res.access_token))
    .catch((err) => console.log(err));
</script>

Please set the values of private_key, client_email and scopes to the object like above, and give it as the argument of GetAccessTokenFromServiceAccount.do(obj).
If you want to use the personal email for the service account, please include the property of userEmail to the object. In this case, the domain-wide delegation is required to be enabled. Ref

Appendix

Sample 1

In the current stage (May 27, 2021), Google API Client Library (gapi) for JavaScript cannot directly use the service account. But, when this library is used, gapi can be used with the service account. The sample script is as follows.

<input type="button" value="Run" onClick="run()" />

<script src="https://cdn.jsdelivr.net/gh/tanaikech/GetAccessTokenFromServiceAccount_js@master/getaccesstokengromserviceaccount_js.min.js"></script>
<script
  async
  defer
  src="https://apis.google.com/js/api.js"
  onload="this.onload=function(){};handleClientLoad()"
  onreadystatechange="if (this.readyState === 'complete') this.onload()"
></script>
<script>
  // Please set the service account.
  const object = {
    private_key: "-----BEGIN PRIVATE KEY-----\n###-----END PRIVATE KEY-----\n",
    client_email: "###",
    scopes: ["https://www.googleapis.com/auth/drive.readonly"],
  };

  const handleClientLoad = () =>
    gapi.load("client", async () =>
      gapi.auth.setToken(await GetAccessTokenFromServiceAccount.do(object))
    );

  function run() {
    gapi.client
      .init({
        discoveryDocs: [
          "https://www.googleapis.com/discovery/v1/apis/drive/v3/rest",
        ],
      })
      .then(() => {
        gapi.client.drive.files
          .list({
            pageSize: 10,
            fields: "files(name)",
          })
          .then(({ body }) => {
            console.log(body);
          });
      });
  }
</script>

When this script is run, the file list of the Google Drive of the service account is obtained.
For example, when an error like Failed to execute 'postMessage' on 'DOMWindow': The target origin provided ('file://') does not match the recipient window's origin ('null'). occurred, please try to run the HTML on the server instead of the local PC.

Licence

MIT

Author

Tanaike

If you have any questions and commissions for me, feel free to tell me.

Update History

v1.0.0 (May 27, 2021)
1. Initial release.

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