var dateStart = new Date('2018-12-05');
var dateEnd = new Date('2018-12-06');
var day = Math.abs(dateEnd - dateStart) / (1000 * 60 * 60 * 24);
//Math.abs() 方法可返回一個數的絕對值
console.log('相差天數:',day); // 1
var dateStart = new Date('2018-12-05');
var dateEnd = new Date('2018-12-06');
var day = Math.abs(dateEnd - dateStart) / (1000 * 60 * 60 * 24);
//Math.abs() 方法可返回一個數的絕對值
console.log('相差天數:',day); // 1