count-awake-at-4am.js

// from https://sleep-cloud.appspot.com/fetchRecords
var sleeps = require('./sleeps.json').sleeps
const todate = n => {
    const d = new Date(n)
    return `${d.getFullYear()}-${d.getMonth()+1}-${d.getDate()}`
}
//var earliest = todate(sleeps[sleeps.length - 1].toTime)
//console.log(earliest)
const all = {}
sleeps.forEach(({fromTime, toTime}) => {
    const from = new Date(fromTime)
    const target = new Date(fromTime)
    target.setHours(4, 0, 0, 0)
    // if from is after 4am, move 4am to next day
    if (from > target) target.setDate(target.getDate()+1)
    const key = todate(target)
    if (toTime < target) {
        if (!all[key]) all[key] = false
    } else {
        all[key] = true
    }
})
console.log(all)