<textarea class="form-control" onClick="do_resize(this)" rows="10"
cols="150" id ="textvalue" style="margin-top: 0px; margin-bottom:
0px; height: 316px;">some text </textarea>

function do_resize(textbox) {
    var maxrows=50;
    var txt=textbox.value;
    var cols=textbox.cols;

    var arraytxt=txt.split('n');
    var rows=arraytxt.length;

    for (i=0;i<arraytxt.length;i++){
        rows+=parseInt(arraytxt[i].length/cols);
    }
    if (rows>maxrows) {
        document.getElementById("textvalue").rows = rows
    }else{
        document.getElementById("textvalue").rows = rows
    }
}