Error: TypeError: undefined is not an object in Java Script

Question

I am new to javascript and I am experimenting with some data to learn about the arrays. unfortunately, I am receiving error as

" Error: TypeError: undefined is not an object in Java Script(evaluating 'dateArray[count] = dateInput[i]')"

what am I doing wrong?

var dateInput = ["18-Sep-2018", "19-Sep-2018", "20-Sep-2018", "21-Sep-2018", "22-Sep-2018"];
var msInput = [86.69, 86.69, 86.76, 86.86, 86.97];
var hsdInput = [79.58, 79.58, 79.58, 79.58, 79.58];
var startDate, endDate, count;
var dateArray, msArray, hsdArray = new Array();
count = 0;
startDate = "18-Sep-2018";
endDate = "21-Sep-2018";

function createArray() {
    for (i = 0; i < dateInput.length; i = i + 1) {
        if (dateInput[i] >= startDate && dateInput[i] <= endDate) {
            dateArray[count] = dateInput[i];
            count = count + 1;
        }
    }
}
createArray();
console.log(msArray);

pL4Gu33 · Accepted Answer · 2018-09-22 07:20:40Z

1

You should write this:

var dateArray = [], msArray = [], hsdArray = [];

because in var dateArray, msArray, hsdArray = new Array(); dateArray and msArray are undefined

answered Sep 22, 2018 at 7:20

pL4Gu33

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Comments

Anand Undavia · Accepted Answer · 2018-09-22 07:21:03Z

1

The issue is you have not initialized the dateArray variable.

var dateArray = new Array(), // <-- initialize this with new Array() or []
    msArray = new Array(), // <-- Might wanna initialize this too
    hsdArray = new Array();

answered Sep 22, 2018 at 7:21

Anand Undavia

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Comments

Shubham Gupta · Accepted Answer · 2018-09-22 08:01:17Z

0

The error is self-explanatory you are trying to treat undefined as an object which means you are doing some operation like

undefined[key] = 'something'

OR

undefined.key

In your code, the problem is in the following line.

var dateArray, msArray, hsdArray = new Array();

Here dateArray and msArray are undefined. Change this to

var dateArray = [], msArray = [], hsdArray = [];

OR

var dateArray = new Array(), msArray = new Array(), hsdArray = new Array();

OR (to avoid such confusion in future cases declare var separately)

var dateArray = new Array();
var msArray = new Array();
var hsdArray = new Array();

answered Sep 22, 2018 at 8:01

Shubham Gupta

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