方法一

使用Electron-builder官方提供的接口，在你的electron-builder.yml配置文件里配置afterAllArtifactBuild属性.

afterAllArtifactBuild: scripts/afterBuild.js

afterBuild.js:

exports.default = function () {
    console.log('------------------------------------afterBuild------------------------------------------');
    return ['upgrade.json']; // 这个返回的数组就是你想要上传的所有文件路径。
}

方法二

思路

通过调用Github rest API接口进行查询、上传文件操作。

上传文件

创建一个本地文件，这里就叫update.js，代码如下：

const fs = require('fs');
const { Octokit } = require("@octokit/rest");
const yaml = require('js-yaml');
const { version } = require('./package.json');

let uploadUpgradeAsset = async function () {
    const octokit = new Octokit({
        auth: process.env.GH_TOKEN, //GH_TOKEN是你的github的personal access token，需要提前在本地环境中配置，不建议直接把token字符串放到这里，不安全。
    });

    // get Owner & Repository name
    const asset = 'electron-builder.yml';
    const { publish } = yaml.load(fs.readFileSync(asset, 'utf8'));
    console.log('version:', version);

    // upload
    const assetName = 'upgrade.json'; //你要上传的文件名。the asset you want to upload to your release.
    octokit.repos.listReleases({
        owner: publish[0].owner,
        repo: publish[0].repo,
    }).then(res => {
        // console.log('listReleases data:', res.data);
        // 获取id，upload_url，
        const { id, upload_url } = res.data.filter(obj => obj.name === version)[0];
        console.log('id, upload_url', id, upload_url);

        let data = fs.readFileSync(assetName);
        let param = {
            owner: publish[0].owner,
            repo: publish[0].repo,
            release_id: id,
            name: assetName,
            data: data,
            origin: upload_url,
            headers: {
                'content-type': 'application/json',
            },
        };
        console.log('param:', param);
        // 上传
        octokit.repos.uploadReleaseAsset(param).then(response => {
            console.log('uploadAsset success:', response);
        }).catch(error => {
            console.log('uploadAsset error:', error);
        });

    }).catch(err => {
        console.log('listReleases error:', err);
    });
}
uploadUpgradeAsset();

配置package.json

"scripts": {
  "pack:win": "run-s build:win upload",
  "build:win": "electron-builder --win -p always",
  "upload": "node update.js",
}