Question

I have a table with n number of rows with checkboxes and a what i want to do is if i select a checkbox the value should go to the text area, so i stored all elements in an array first, but it isnt happening, as you can see i added alerts as well to check it out. please help.

window.onload = function () { 
    var oRows = document.getElementById('rnatable').getElementsByTagName('tr');
    var iRowCount = oRows.length;
    alert('Your table has ' + iRowCount + ' rows.');

    var i = 0;
    cb = new Array(iRowCount);
    while (i <= iRowCount) {
        var id = 'check'+ i;
        cb[i] = document.getElementById(id);
        i++;
    }
    //alert('Your table has ' + cb[i].value + ' rows.');
    for(var a=0; a < iRowCount; a++) {
        var fasta = document.getElementById('fasta');
        if(cb[a].checked) {
            fasta.value = cb.value + ","; 
        };
    };
}

Answer 1

Are you seeing an error in the console? I suspect that when while (i <= iRowCount) runs when i === iRowCount that document.getElementById(id) isn’t yielding a result, and that then when you use that value, bad things happen.

Also, each lap through the fasta loop overwrites the previous value. You probably want something like fasta.value += cb.value + ","; instead.