How can I populate a javascript array with values from a database using PHP?

Collect the values in an array and convert it to JSON with json_encode:

$array = array();
while ($row = mysql_fetch_assoc($result)) {
    $array[] = $row['key'];
}
echo 'var array = '.json_encode($array).';';

Answer 1: yes, it can be done.

Answer 2: Here's how:

$js_array = "[";
$result = mysql_query("some query of yours");
while( $row=mysql_fetch_array($result, MYSQL_NUM) ) {
    $js_array .= $row[0]; // assuming you just want the first field 
                          // of each row in the array
    $js_array .= ",";
}
$js_array{ strlen($js_array)-1 } = ']';

echo "var db_array = $js_array ;";

Cheers!

<script language="javascript1.2">
var arr = new array(<?php 
$result = mysql_query("select .... ");
$count = mysql_num_rows($result);
if($count>0){
  for( $i=0;$i<$count-1;$i++) {
    $row = mysql_fetch_row($result);
    echo $row[0],',';
  }
  $row = mysql_fetch_row($result);
  echo $row[0],',';
}
?>);
</script>

If you can loop through the database contents, creating an array is simple:

echo "var myArray = [";

Loop through array here and add commas to separate values.

echo "];";

Your myArray variable will be available client-side. It should look something like:

var myArray = [1, 3, 2, 4];

Alternatively and to avoid an extra comma due to loop-based string concatenation, you can write the variable to the client as follows:

echo "var myArray = [];"

...and do the following for each data row:

echo "myArray.push($db_data);"

This is effective, though not quite as clean as the previous approach. You will end up with code similar to the following:

var myArray = [];

myArray.push(3);
myArray.push(5);
myArray.push(1);

alert(myArray); // will display "3, 5, 1"

My apologies for not being too familiar with PHP, but this is something that can be done with any server-side language.