Getting type error on Javascript two dimensional array

Question

I assign array[0][0] and array[0][1] with predefined variable and rest of the array with the data from php variable with for loop.

function getDistance(){
    var row = JSON.parse(document.getElementById('rows').innerHTML);
    var markers = JSON.parse(document.getElementById('markers').innerHTML);
    var distance = new Array(row);
    for (var i = 0; i < row; i++) {
        distance[i] = new Array(2);
    }
    distance [0][0]= 16.78789;
    distance [0][1]= 96.15291;
    for(var i = 0; i<markers.length; i++){
        var latt = parseFloat(markers[i].latitude);
        var longt = parseFloat(markers[i].longitude);
        distance [i+1][0]= latt;
        distance [i+1][1]= longt;
    }
}

And this is where I get error in distance[i+1]. Its say distance[i+1] is undefined. The code is working fine if i assign distance[i][0] in for loop it means that I assign to distance[0][0] and [0][1]. Its doesn't allow me to start at array index 1. This code is working there is nothing wrong with my variables I get all the variable I want only at array indexing getting error.

function getDistance(){
var row = JSON.parse(document.getElementById('rows').innerHTML);
var markers = JSON.parse(document.getElementById('markers').innerHTML);
var distance = new Array(row);
for (var i = 0; i < row; i++) {
  distance[i] = new Array(2);
}
for(var i = 0; i<markers.length; i++){
    var latt = parseFloat(markers[i].latitude);
    var longt = parseFloat(markers[i].longitude);
    distance [i][0]= latt;
    distance [i][1]= longt;
}
}

what is the value of row ... it better be one greater than the value of markers.length - because i+1 — Jaromanda X
– Jaromanda X, Commented Jul 27, 2018 at 3:40
Javascript doesn't support multi-dimensional arrays, so of course the array you try to access does not exist if you didn't create it. did you create the i+1 array before trying to put elements in it? no. — mpm
– mpm, Commented Jul 27, 2018 at 3:42
I edited my question and its working fine and I also try with marker.length and get same error — Ye Yint
– Ye Yint, Commented Jul 27, 2018 at 3:54

Rmanaf · Accepted Answer · 2018-07-27 03:57:38Z

1

Make sure "row" is a number after You parse that JSON, otherwise you have an array included a single "string" or "object" item at 0

var row = parseInt(JSON.parse(document.getElementById('rows').innerHTML));

and then check "distance" length

var distance = new Array(row);
console.log(distance)

answered Jul 27, 2018 at 3:57

Rmanaf

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3 Comments

Ye Yint Over a year ago

I edited my question everything is fine in second code.

Rmanaf Over a year ago

I checked your code on my pc and I added [{"a" : "1"},{"b" : "2"}] as the innerHtml of markers and rows, then distance[i+1] was undefined , so i changed rows to a fixed number in first loop for (var i = 0; i < row; i++) {...} and problem solved. try this: for (var i = 0; i <= row.length; i++) {...}

Ye Yint Over a year ago

It working now i changed for(var i = 1; i < distance.length; i++) and used distance[i][0]....

Osama · Accepted Answer · 2018-07-27 04:21:53Z

1

Array is zero index so you should compare to row-1

for (var i = 1; i < distance.length-1; i++) {

And also remove +1 in this lines

distance [i][0]= latt;
distance [i][1]= longt;

edited Jul 27, 2018 at 4:21

answered Jul 27, 2018 at 3:40

Osama

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6 Comments

Ye Yint Over a year ago

if i start loop at var i=1 i can't get values from markers at index 0

Osama Over a year ago

You just fill the array here in this code while using it set i to 0

Ye Yint Over a year ago

Thank u sir its working now but i need to use distance.length instant of distance.length-1 to get all my data.

Osama Over a year ago

Ok make it that but you have to check if i <distance.length if yes do the code else do nothing or return null

Osama Over a year ago

Or use while loop instead of for loop

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