js计算两个日期的间隔天数

getDateNum: (startDate = ``) => {
    console.log(`startDate`, startDate)
    if (!startDate) {
        return 0
    }
    // 获取今日日期
    let localDate = new Date()
    let yearData = localDate.getFullYear()
    let mouthData = localDate.getMonth() + 1
    let dayData = localDate.getDay()
    var dateStart = new Date(startDate)
    console.log(`dayData`, dayData)
    var dateEnd = new Date(`${yearData}-${mouthData}-${dayData}`)
    var difValue = (dateEnd - dateStart) / (1000 * 60 * 60 * 24)
    console.log(`difValue`, difValue)
    return parseInt(Math.abs(difValue))
},

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