zotero-api-client-upload-example.js

const api = require('./src/api');
const fs = require('fs');
const filedata = fs.readFileSync('picture.jpg');

// live api, vexlign credentials
const APIKEY = '';
const USERID = '';
const ITEM_KEY = '';

(async () => {
	try {
		const template = (await api()
			.template('attachment')
			.get({ linkMode: 'imported_file' })).getData();
		
		const item = {
			...template,
			title: 'attached picture',
			parentItem: ITEM_KEY,
			filename: 'picture.jpg',
			contentType: 'image/jpeg',
		};
    
		const attachmentItem = (await api(APIKEY)
			.library(USERID)
			.items()
			.post([item])).getEntityByIndex(0);

		const response = await api(APIKEY)
			.library(USERID)
			.items(attachmentItem.key)
			.attachment('picture.jpg', filedata.buffer)
			.post();

	} catch(e) {
		// , uploadResponse, registerResponse
		console.warn(e, e.reason, e.message, e.options);
	}
})();