Javascript 2D数组生成未按预期工作

Question

I am new here, and to programming as well. Anyway, to get in topic I wrote the following program with the purpose of generating a 2 dimensional array in JavaScript, and then displaying its elements in a table. However, in the place where the value of the i row array index was supposed to show (like 1 in first row, then 2 in the second row, etc), the number 10 shows instead. So, I'd appreciate if someone could explain what I did wrong. Here is the code:

<table border="1">
    <script>
        var array1 = [];
        var array2 = [];
        for (var i = 0; i < 10; i++) {
            for (var j = 0; j < 10; j++) {
                array2[j] = (i + 1) + "-" + (j + 1);
            }
            array1[i] = array2;
        }

        for (var i = 0; i < 10; i++) {
            document.write("<tr>");
            for (var j = 0; j < 10; j++) {
                document.write("<td>" + array1[i][j] + "</td>");
            }
            document.write("</tr>");
        }
    </script>
</table>

Answer 1

You are adding the same array to array1 , again and again. Instead you need to create new arrays every time.

var array1 = [];

for (var i = 0; i < 10; i++ ) {
    var array2 = [];
    for (var j = 0; j < 10; j++) {
        array2[j] = (i+1) + "-" + (j+1);
    }
    array1[i]=array2;
}

But normally, this will be done with Array.prototype.push method, like this

var array1 = [];

for (var i = 0; i < 10; i++ ) {
    var array2 = [];
    for (var j = 0; j < 10; j++) {
        array2.push((i+1) + "-" + (j+1));
    }
    array1.push(array2);
}

Answer 2

You can create new array each time after assigned array2 to array1 , something like this

array2=[];

on

for (var i = 0; i < 10; i++ ) {
    for (var j = 0; j < 10; j++) {
        array2[j] = (i+1) + "-" + (j+1);

    }
    array1[i]=array2;
    array2=[]; //created new array each time after array2 assigned
}