expo-mail-composer/src/ExpoMailComposer.web.ts

import qs from 'query-string';

import { MailComposerOptions, MailComposerResult, MailComposerStatus } from './MailComposer.types';

function removeNullishValues(obj) {
  for (const propName in obj) {
    if (obj[propName] == null) {
      delete obj[propName];
    }
  }
  return obj;
}

function checkValue(value?: string[] | string): string | null {
  if (!value) {
    return null;
  }

  const arr = Array.isArray(value) ? value : [value];
  return arr.join(',');
}

export default {
  get name(): string {
    return 'ExpoMailComposer';
  },
  async composeAsync(options: MailComposerOptions): Promise<MailComposerResult> {
    const email = removeNullishValues({
      cc: checkValue(options.ccRecipients),
      bcc: checkValue(options.bccRecipients),
      subject: options.subject,
      body: options.body,
    });

    const query = qs.stringify(email);
    const queryComponent = query ? '?' + query : '';
    const to = checkValue(options.recipients) || '';
    const mailto = `mailto:${to}${queryComponent}`;

    window.open(mailto);

    return { status: MailComposerStatus.UNDETERMINED };
  },
  async isAvailableAsync(): Promise<boolean> {
    return true;
  },
};