How can I convert this JSON from PHP to a Javascript array

Question

I am trying to assign a json array to a javascript array so that my JS functions can access the array. So I have an ajax call to MySQL db to get a JSON array of data:

var data = [];
    $.ajax({
      type:"post",
      url:"position.php",
      dataType:'json',
      success:function(jsonarray){
                data=$.parseJSON(jsonarray);
               }
     });

position.php:

<?php
include 'dbconnect.php';  

$sql = "SELECT pid, posX, posY FROM posTable;";
$result = $conn->query($sql);
$myrows = $result->num_rows;
$return=array();

if ($result->num_rows>0){

while($row=$result->fetch_assoc()){      
     $return[]=array((int)$row['pid'],(int)$row['posX'],(int)$row['posY']);        
     }

}else{
echo "[]";
}
echo json_encode($return);
$conn->close();
?>

This gives an output like this:

[[1,749,1000],[2,855,986],[3,955,946],[4,1037,934],[5,1111,912]]

And from this I want the following two dimensional array so that I can access its memebers in this form:

data[i][j]

data => [[1,749,1000],[2,855,986],[3,955,946],[4,1037,934],[5,1111,912]]

However when I execute the code I keep getting the following error:

Uncaught SyntaxError: Unexpected token , in JSON at position 1

What am I doing wrong?

Quentin · Accepted Answer · 2016-06-02 09:47:08Z

2

jQuery will automatically parse a JSON response before populating the success function's first argument.

$.parseJSON(jsonarray); calls toString() on your array and then tries to parse it as JSON, which it isn't (because Array.prototype.toString() doesn't convert to JSON).

Just don't try to parse it again.

answered Jun 2, 2016 at 9:47

Quentin

948k136 gold badges1.3k silver badges1.4k bronze badges

Sign up to request clarification or add additional context in comments.

8 Comments

Emmanuel Over a year ago

I now assigned jsonarray to data without the json parsing and it takes care of the error. How can I see that data is now properly two dimensional? i.e. how can I see that data is truly of the form data[i][j]

Quentin Over a year ago

console.log is the usual choice for inspecting an element

Emmanuel Over a year ago

When I try this, I get 0 undefined error: ` for(var i=0;i<2;i++){ for(var j=0;j<3;j++){ alert(data[i][j]); } }` UPDATE: From console I can see that data is indeed a 2D array

Quentin Over a year ago

Are you sure you get an undefined error and not just an alert where the value is a stringified undefined value?

Emmanuel Over a year ago

I get : Cannot read property '0' of undefined Alert does not pop up

|

Collectives™ on Stack Overflow

How can I convert this JSON from PHP to a Javascript array

1 Answer 1

8 Comments

Your Answer

Linked

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

8 Comments

Your Answer

Sign up or log in

Post as a guest

Linked

Related