export interface Model { major: boolean minor: boolean seventh: boolean minorSeventh: boolean majorSeventh: boolean bpm: number beatsPerChord: number } let init: Model = { major: true, minor: false, seventh: false, minorSeventh: false, majorSeventh: false, bpm: 90, beatsPerChord: 4 } let key: string = 'options' export function load(): Model { let str = localStorage[key] return str && JSON.parse(str) || init } export function save(options: Model): void { localStorage[key] = JSON.stringify(options) }