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POJavascript TypeError: Array is undefined
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  1. POJavascript TypeError: Array is undefined
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    copied!<p>to test some things in javascript I am building a small minesweeper.</p> <p>The following code is the initialization of the two-dimension array <code>P.field</code>. Afterwards a number of random fields are getting filled with an <code>x</code>, symbolizing that there's a mine on this field.</p> <pre><code>P.field = new Array(num); for (var i = 0; i &lt; P.field.length; i++) P.field[i] = new Array(num); $.each(P.field, function(index, key) { $.each(key, function(i, k) { P.field[index][i] = '-'; }); }); var arr = []; while (arr.length &lt; 10) { var found = false; var randomnumber = Math.ceil(Math.random()*(num*num-1)); for (var i = 0; i &lt; arr.length; i++) if (arr[i] == randomnumber) { found = true; break; } if (!found) arr[arr.length] = randomnumber; } for (var i = 0; i &lt; arr.length; i++) { P.field[ Math.floor(arr[i]/num) ][ Math.floor(arr[i]-Math.floor(arr[i]/num)*num)-1 ] = 'x'; } </code></pre> <p>However, in my algorithm for counting the mines in surrounding fields, I get the console error <code>TypeError: P.field[(r+1)] is undefined</code>. Every field (except of those from the last row) returns this error, which is something I can't quite understand.</p> <p><code>P.field[rows][columns]</code> has a length of 10 per dimension in my tests ([10][10]). When I try to get the value of <code>P.field[9][0]</code> to <code>P.field[9][9]</code> there's nothing wrong. However when I adress any smaller row, this exception kicks in (<code>P.field[0 + 1][0]</code>, <code>P.field[3 + 1][6]</code>, and what so ever)...</p> <p>I hope someone can tell me why.</p> <p><strong>edit</strong></p> <p>More code:</p> <pre><code>onReady: function() { $('#sweeper table').on('click', 'td', function(e) { var row = $(this).parent().attr('class'); // Class represents the index of the array var column = $(this).attr('class'); // Class represents the index of the array P.openField(row, column, $(this)); }); }, openField: function(r, c, e) { if ( P.field[r][c] == 'x' ) { e.addClass('mine'); } else { e.html( P.surroundingMineCount(r, c) ); e.addClass('opened'); } }, surroundingMineCount: function(r, c) { var count = 0; if ( P.field[r][c-1] == 'x' ) count++; if ( P.field[r-1][c-1] == 'x' ) count++; if ( P.field[r][c+1] == 'x' ) count++; if ( P.field[r-1][c] == 'x' ) count++; if ( P.field[r-1][c+1] == 'x' ) count++; if ( P.field[r+1][c] == 'x' ) count++; if ( P.field[r+1][c-1] == 'x' ) count++; return count; }, </code></pre> <p>Right now I have no validation if the r+1 or r-1 is actually a valid index for that array (I had one in, but removed it for testing). However that can't really be the error, because I even get errors in the middle of the table.</p>
 

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