ES6対応 GAS、Execution API実行用認証スクリプト 参考 : https://developers.google.com/apps-script/guides/rest/quickstart/js

GasAuth.js

// Your Client ID can be retrieved from your project in the Google
// Developer Console, https://console.developers.google.com
const CLIENT_ID = 'CHANGE_YOUR_CLIENT_ID';
const SCOPES = ['CHANGE_YOUR_SCOPES'];
const SCRIPT_ID = 'CHANGE_YOUR_SCRIPT_ID';

//callback events
export const COMPLETE = "complete";
export const ERROR = "error";

export default class GasAuth {
    constructor(cb) {
        this.cb = cb;
        this.init();
    }

    init() {
        window.checkAuth = ()=> {
            this.auth();
        };
        window.handleAuthClick = ()=> {
            this.handleAuthClick();
        };
        let script = document.createElement('script');
        script.src = "https://apis.google.com/js/client.js?onload=checkAuth";
        document.body.appendChild(script);
    }

    /**
     * Check if current user has authorized this application.
     */
    auth() {
        gapi.auth.authorize(
            {
                'client_id': CLIENT_ID,
                'scope': SCOPES.join(' '),
                'immediate': true
            }, (authResult)=> {
                this.handleAuthResult(authResult);
            });
    }

    handleAuthResult(authResult) {
        if(authResult && !authResult.error) {
            this.cb(COMPLETE);
        } else {
            this.cb(ERROR);
        }
    }

    handleAuthClick() {
        gapi.auth.authorize(
            {
                client_id: CLIENT_ID,
                scope: SCOPES.join(' '),
                immediate: false
            }, (authResult)=> {
                this.handleAuthResult(authResult);
            });
        return false;
    }

    /**
     * Calls an Apps Script function to list the folders in the user's
     * root Drive folder.
     */
    callScriptFunction(funcname, params, cb, devMode) {
        console.log("callScriptFunction");
        devMode = devMode || false;

        // Create an execution request object.
        var request = {
            'function': funcname,
            'parameters': params,
            'devMode': devMode
        };

        // Make the API request.
        var op = gapi.client.request({
            'root': 'https://script.googleapis.com',
            'path': 'v1/scripts/' + SCRIPT_ID + ':run',
            'method': 'POST',
            'body': request
        });

        op.execute(function(resp) {
            if(resp.error && resp.error.status) {
                // The API encountered a problem before the script
                // started executing.
                console.log('Error calling API:');
                console.log(JSON.stringify(resp, null, 2));
            } else if(resp.error) {
                // The API executed, but the script returned an error.

                // Extract the first (and only) set of error details.
                // The values of this object are the script's 'errorMessage' and
                // 'errorType', and an array of stack trace elements.
                var error = resp.error.details[0];
                console.log('Script error message: ' + error.errorMessage);

                if(error.scriptStackTraceElements) {
                    // There may not be a stacktrace if the script didn't start
                    // executing.
                    console.log('Script error stacktrace:');
                    for(var i = 0; i < error.scriptStackTraceElements.length; i++) {
                        var trace = error.scriptStackTraceElements[i];
                        console.log('\t' + trace.function + ':' + trace.lineNumber);
                    }
                }
            } else {
                // The structure of the result will depend upon what the Apps
                // Script function returns. Here, the function returns an Apps
                // Script Object with String keys and values, and so the result
                // is treated as a JavaScript object (folderSet).
                var result = resp.response.result;
                //console.log("result:", result);
                if(cb) {
                    cb(result);
                }
            }
        });
    }
}

usage.js

import GasAuth from 'GasAuth';
import {COMPLETE, ERROR} from 'GasAuth';

const gasAuth = new GasAuth(callback);

function callback(type){
  switch(type){
    case "error":
      break;
    case "complete":
      gasAuth.callScriptFunction("nanika", [], (res)=> {
        console.log("result:", res);
      }, false);
      break;
  }
  
}