Calculation with Array values not working in JS

Question

in my current project I need a Pie Chart in which calculated values should be displayed. I have now five values as array, which I need to add, so that I have the desired value. But now I am a bit confused, because no matter if I convert the arrays to sting, or use them directly in the addition, they are always lined up and not added. What am I missing here?

In a subtraction directly after the calculation works, but here I still have a date value (number of days in the month) in the calculation. Why does this calculation work?

My Problem

For example I get here "02400" as result and not "6".

var training = training_intervall + training_longrun + training_speedwork + training_stabilisation + training_competition;

My JS function:

function userDiaryMonthTrainingStats(user_id) {

    $.ajax({
        url: "../diary/includes/training/diary-training-monthly-training-stats.php?user_id=" + user_id,
        type: "GET",
        success: function(monthly_training_stats) {

            var training_intervall = [];
            var training_longrun = [];
            var training_speedwork = [];
            var training_stabilisation = [];
            var training_competition = [];
            var training_injury = [];

            for(var i in monthly_training_stats) {
                training_intervall.push(monthly_training_stats[i].training_intervall),
                training_longrun.push(monthly_training_stats[i].training_longrun),
                training_speedwork.push(monthly_training_stats[i].training_speedwork),
                training_stabilisation.push(monthly_training_stats[i].training_stabilisation),
                training_competition.push(monthly_training_stats[i].training_competition),
                training_injury.push(monthly_training_stats[i].training_injury)
            }

            var date = new Date();
            var month = date.getMonth() + 1;
            var year = date.getFullYear();
            daysInMonth = new Date(year, month, 0).getDate();

            training_intervall = training_intervall.toString();
            training_longrun = training_longrun.toString();
            training_speedwork = training_speedwork.toString();
            training_stabilisation = training_stabilisation.toString();
            training_competition = training_competition.toString();

            var training = training_intervall + training_longrun + training_speedwork + training_stabilisation + training_competition;
            var training_free = daysInMonth - training_intervall - training_longrun - training_speedwork - training_stabilisation - training_competition - training_injury;

            var userMonthlyTrainingStatsData = {
                datasets:  [{
                    data: [training, training_injury, training_free],
                    backgroundColor: ['#36a2eb', '#e33b3b', '#4bc07d']
                }],

                labels: [
                    'Training',
                    'Injury',
                    'Free'
                ]
            };

            ........

        }
    })
}

+ is also used for string concatenation. If one operand is of type string the result is also a string. — Andreas
– Andreas, Commented Aug 10, 2021 at 17:59
I get 6 different values from the DB with different names and then separate them into one array value each in one to one variable before the toString() function. — Scenus
– Scenus, Commented Aug 10, 2021 at 18:11

user4308987 · Accepted Answer · 2021-08-10 18:11:06Z

1

use parseInt() to change from a string to int then you can add the strings as they are now numbers

var training = parseInt(training_intervall) + parseInt(training_longrun) + parseInt(training_speedwork + parseInt(training_stabilisation) + parseInt(training_competition);

if you want the result back to a string simply put after this

training=""+training

answered Aug 10, 2021 at 18:11

user4308987

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Comments

Nat · Accepted Answer · 2021-08-10 18:16:06Z

1

Two problems in your code:

training_intervall and the other 4 variables you want to add are arrays, you should iterate them.
The values are strings, using + with strings results in a new concatenated string. To convert easily a string number to a number (example "1" to 1), you can:

const myString = "1"
const myNumber = myString * 1 // myNumber = 1

answered Aug 10, 2021 at 18:16

Nat

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