javascript array input user and average calculation

Question

I have this problem to solve. It sounds maybe simple but I am a total beginner. here is my code so far but there is only one window that appears when I run it. Thank you for your advices and help

var years= prompt("Enter the number of years: "); // Number of years
var rainFall = new ArrayList();

while (years < 1) {

    alert("Invalid. Enter 1 or greater: ");
    years =prompt("Enter a year: ");
}

for (var y = 1; y <= years; y++) {

    for (var m = 1; m <= NUM_MONTHS; m++) {

        alert("Year " + y + " month " + m + ": ");
        monthRain = prompt("enter rainfall for a month ");
        rainfall.add(monthRain);
    }
}

 alert("\nNumber of months: " + (years * NUM_MONTHS) + "Total rainfall: " + calculateTotalRainFall(rainFall) + " inches" + "Average monthly rainfall: " + calculateAverageRainFall(rainFall) + " inches");

Hi, try changing rainfall.add(monthRain); to rainfall.push(monthRain); — Mansi Parekh
– Mansi Parekh, Commented Jul 20, 2015 at 12:28

num8er · Accepted Answer · 2015-07-20 12:52:18Z

1

    Array.prototype.sum = function() {
      var total = 0;
      for(var i in this) {
        var i = parseFloat(this[i]);
        if(i>=0) {
          total += i;
        }
      }
      return total;
    };

    Array.prototype.avg = function() {
      var avg = (this.length>0)? parseFloat(this.sum()/this.length) : 0;
      avg = parseFloat(parseInt(avg*100)/100);
      return avg;
    };

    var years = parseInt(prompt("Enter the number of years: ")); // Number of years

    var rainFall = [];

    while (years < 1) {
      alert("Invalid. Enter 1 or greater: ");
      years = parseInt(prompt("Enter a year: "));
    }

    var NUM_MONTHS = 12;
    for (var y = 1; y <= years; y++) {
      for (var m = 1; m <= NUM_MONTHS; m++) {
        alert("Year " + y + " month " + m + ": ");

        var monthRain = parseFloat(prompt("enter rainfall for a month "));
        if(monthRain>=0) {
          rainFall.push(monthRain);
        }
      }
    }

 if(years<1) years = 0;
 alert("\nNumber of months: " + (years * NUM_MONTHS) + "   Total rainfall: " + rainFall.sum() + " inches" + "   Average monthly rainfall: " + rainFall.avg() + " inches");

OR:

    function sumArray (items) {
      var total = 0;
      for(var i in items) {
        var i = parseFloat(items[i]);
        if(i>=0) {
          total += i;
        }
      }
      return total;
    };

    function avgArray(items) {
      var sum = sumArray(items);
      var avg = (items.length>0)? parseFloat(sum/items.length) : 0;
      avg = parseFloat(parseInt(avg*100)/100);
      return avg;
    };

    var years = parseInt(prompt("Enter the number of years: ")); // Number of years

    var rainFall = [];

    while (years < 1) {
      alert("Invalid. Enter 1 or greater: ");
      years = parseInt(prompt("Enter a year: "));
    }

    var NUM_MONTHS = 12;
    for (var y = 1; y <= years; y++) {
      for (var m = 1; m <= NUM_MONTHS; m++) {
        alert("Year " + y + " month " + m + ": ");

        var monthRain = parseFloat(prompt("enter rainfall for a month "));
        if(monthRain>=0) {
          rainFall.push(monthRain);
        }
      }
    }

 if(years<1) years = 0;
 alert("\nNumber of months: " + (years * NUM_MONTHS) + "   Total rainfall: " + sumArray(rainFall) + " inches" + "   Average monthly rainfall: " + avgArray(rainFall) + " inches");

edited Jul 20, 2015 at 12:52

answered Jul 20, 2015 at 12:31

num8er

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2 Comments

user5134938 Over a year ago

Thank you for your answer but it is far from what I have learned in class now I am not supposed to use function yet. Just basic pseudocode

user5134938 Over a year ago

sorry I meant to not use function but I keep your answers for my next works. Thanks a lot for your time

Mansi Parekh · Accepted Answer · 2015-07-20 12:34:03Z

0

try changing rainfall.add(monthRain); to rainfall.push(monthRain);

answered Jul 20, 2015 at 12:34

Mansi Parekh

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Comments

Soron · Accepted Answer · 2015-07-20 12:40:12Z

It looks like your core mistake was using the Java ArrayList class, when you should have been using the JavaScript Array class. Keep in mind that Java and JavaScript are not related (the name is confusing, yes).

If you change new ArrayList() to new Array(), and rainfall.add to rainFall.push (note the capitalization change as well), then it seems to work.

If you have access to a JavaScript console inspector (accessible in Chrome, for instance, with ctrl-shift-J), you can look for the JS errors that occur in your code, such as the error encountered when ArrayList couldn't be found.

Fixed below. I've also added the missing NUM_MONTHS constant (which I assume you had elsewhere).

var NUM_MONTHS = 12;
var years= prompt("Enter the number of years: "); // Number of years

// CHANGE: use "Array", not "ArrayList". You could also use "var rainFall = [];", which I find
var rainFall = new Array();

while (years < 1) {

    alert("Invalid. Enter 1 or greater: ");
    years =prompt("Enter a year: ");
}

for (var y = 1; y <= years; y++) {

    for (var m = 1; m <= NUM_MONTHS; m++) {

        alert("Year " + y + " month " + m + ": ");
        monthRain = prompt("enter rainfall for a month ");
        // CHANGE: use "push()" method of Array, and use camelCase for variable name consistency
        rainFall.push(monthRain);
    }
}

alert("\nNumber of months: " + (years * NUM_MONTHS) + "Total rainfall: " + calculateTotalRainFall(rainFall) + " inches" + "Average monthly rainfall: " + calculateAverageRainFall(rainFall) + " inches");

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