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JavaScript JavaScript Basics (Retired) Working With Numbers Doing Math

Posted by Mithun B
Mithun B
1,978 Points

I wrote a program to show the days, minutes and seconds a person lived till his age

    var secondsInMinute = 60;
    var minutesInHour = 60;
    var hoursInDay = 24;
    var daysInYear = 365;
    var myName = prompt("What is your name?");
    var myAge = prompt("What is your age?");
    var secondsInHour = secondsInMinute * minutesInHour;
    var secondsInDay = secondsInHour * hoursInDay;
    var totalDaysAlive = myAge * daysInYear;
    var totalHoursAlive = hoursInDay * totalDaysAlive;
    var totalMinutesAlive = totalHoursAlive * minutesInHour;
    var totalSecondsAlive = totalMinutesAlive * secondsInMinute;

    document.write(myName + ", You lived for:<b> " + totalDaysAlive + " </b>days<br/>");
    document.write(myName + ", You lived for:<b> " + totalHoursAlive + " </b>Hours <br/>");
    document.write(myName + ", You lived for:<b> " + totalMinutesAlive + " </b>Hours <br/>");
    document.write(myName + ", You lived for:<b> " + totalSecondsAlive + " </b>Seconds <br/>");

Is this write?

I also wrote some CSS for this program and it looks cool. Tell me if you find any mistakes in this program.

PS: I am loving JavaScript. It's different from PHP and users don't even need to refresh the page :D

Thanks

3 Answers

Chris Shaw
Chris Shaw
26,676 Points
Chris Shaw
Chris Shaw
26,676 Points

Hi Mithun,

The only issue I see is the following line as when a user enters their age it will be a string so to ensure 100% consistency it's better to parse it first as an integer.

var totalDaysAlive = parseInt(myAge, 10) * daysInYear;

One thing I would just from a fail safe point of view is add error checking to both your prompts to ensure a valid name and valid age were entered which will ensure your code doesn't break and cause issues.

var myName = prompt("What is your name?");

if (!myName) {
    alert("You didn't enter a valid name");
    return false;
}

var myAge = prompt("What is your age?"),
    myAge = parseInt(myAge, 10);

if (isNaN(myAge)) {
    alert("You didn't enter a valid age");
    return false;
}

You can get a lot more advanced with these kinds of checks but I wanted to keep it simple.

moath alqutoob
moath alqutoob
2,450 Points

Chris Upjohn can you pleas explane me this cod

var totalDaysAlive = parseInt(myAge, 10) * daysInYear; what the different between this ; var totalDaysAlive = myAge * daysInYear;

2-and i wont explan this

var myName = prompt("What is your name?");

if (!myName) { alert("You didn't enter a valid name"); return false; }

var myAge = prompt("What is your age?"), myAge = parseInt(myAge, 10);

if (isNaN(myAge)) { alert("You didn't enter a valid age"); return false; }

Chris Shaw
Chris Shaw
26,676 Points
Chris Shaw
Chris Shaw
26,676 Points

Hi moath alqutoob,

The reason for using parseInt is because the prompt function will always return a string therefore we may not get a consistent result between browsers if we don't first parse the given value as a number which eliminates any inconsistencies.

Mithun B
Mithun B
1,978 Points
Mithun B
Mithun B
1,978 Points

Thanks a lot, Chris. I will definitely keep this in mind.

Thanks again, Mithun

Leon Laci
PLUS
Leon Laci
Courses Plus Student 4,423 Points
Leon Laci
Leon Laci
Courses Plus Student 4,423 Points

What about 366 days in a year?

Chris Shaw
Chris Shaw
26,676 Points
Chris Shaw
Chris Shaw
26,676 Points

I found a nice little hack on Stack Overflow which you can use to determine if it's a leap year.

var isLeapYear = new Date(new Date().getFullYear(), 1, 29).getMonth() === 1;
var daysInYear = isLeapYear ? 366 : 365;
Leon Laci
Leon Laci
Courses Plus Student 4,423 Points

Thanks Chris