Doodle Bookmarklet Wizard for Weekly Recurring Events

doodle.js

javascript: (() => {
    // Whenever you run the bookmarklet, always returns the next Wednesday.
    const nextWednesday = () => {
        let ret = new Date();
        ret.setDate(ret.getDate() + (3 - 1 - ret.getDay() + 7) % 7 + 1);
        return ret.toLocaleDateString('en-US', {
            weekday: 'long',
            year: 'numeric',
            month: 'long',
            day: 'numeric'
        });
    };
    // As a running gag participants can choose between soccer (i.e., come that
    // day) or a random emoji (i.e., not come that day). More emoji => More fun.
    const emojis = '😀😬😁😂😃😄😅😆😇😉😊🙂🙃☺️😋😌😍😘😗'
        .split(/([\uD800-\uDBFF][\uDC00-\uDFFF])/).filter(a => a.length > 1);
    // See https://goo.gl/u3ETG9 for all options, for undocumented options
    // inspect Doodle's HTML
    const options = {
        type: 'text',
        levels: 2,
        locale: 'en',
        title: 'Soccer on ' + nextWednesday(),
        location: 'Indoor soccer hall',
        description: 'Weekly company soccer match',
        name: 'John Doe',
        eMailAddress: 'john.doe@example.com',
        option1: '⚽️  Soccer',
        option2: `${emojis[~~(Math.random() * emojis.length) + 1]} Alternative`,
        hidden: false,
        columnConstraint: 15,
        rowConstraint: 1,
        invitees: ['soccer@example.com']
    };
    // Use HTTP POST so we can pass email addresses and a _blank target so that
    // the bookmarklet opens in a new tab.
    const form = document.createElement('form');
    form.method = 'post';
    form.action = 'https://doodle.com/create/';
    form.target = '_blank';
    const node = document.createElement('input');
    for (name in options) {
        node.name = name;
        node.value = options[name].toString();
        form.appendChild(node.cloneNode());
    }
    document.body.appendChild(form);
    form.submit();
})();

May not work when opened on sites with Content Security Policy (CSP, like this very site where the Gist is hosted). The error message then is…
Refused to send form data to 'https://doodle.com/create/' because it violates the following Content Security Policy directive: "form-action 'self' github.com gist.github.com".