jschan/gulp/res/js/password.js

const charset = 'abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789+/';
const generatePassword = () => {
	if (window.crypto) {
		const buf = new Uint8Array(20); //8 keeps charcodes within range
		window.crypto.getRandomValues(buf);
		return btoa(String.fromCharCode.apply(null, buf));
	} else {
		return new Array(20)
			.fill(null)
			.map(x => charset[Math.floor(Math.random()*charset.length)])
			.join('');
	}
}
setDefaultLocalStorage('postpassword', generatePassword());
setDefaultLocalStorage('name', '');

class syncedField {
	constructor(selector, key, persistent) {
		this.fields = []

		const settingsFields = document.getElementById('settingsmodal').querySelectorAll(selector);
		this.fields = this.fields.concat([...settingsFields]);

		const postForm = document.getElementById('postform');
		if (postForm) {
			const postformFields = postForm.querySelectorAll(selector);
			this.fields = this.fields.concat([...postformFields]);
		}

		const actionForm = document.getElementById('actionform');
		if (actionForm) {
			const actionFields = actionForm.querySelectorAll(selector);
			this.fields = this.fields.concat([...actionFields]);
		}

		this.key = key;
		this.persistent = persistent;
		for (let field of this.fields) {
			field.value = localStorage.getItem(this.key);
			field.addEventListener('input', (e) => { this.update(e) }, false);
		}
	}
	update(e) {
		if (this.persistent) {
			setLocalStorage(this.key, e.target.value);
		}
		for (let field of this.fields) {
			field.value = e.target.value;
		}
	}
}

window.addEventListener('settingsReady', () => {

	new syncedField('input[name="postpassword"]', 'postpassword', true);
	new syncedField('input[name="name"]', 'name', true);

});