Check textarea value

HTML

<form id="f1" action="" method="post">
    <label for="ta1">TextArea</label>
    <br/>
    <textarea id="ta1"></textarea>
    <label for="result">Result:</label>
    <input id="result" type="text"></input>
    <br/>
    <input type="submit" value="verify"></input>
</form>
<input type="submit" value="verify"></input>

JavaScript

var ta1 = document.getElementById("ta1");
var result = document.getElementById("result");
f1.onsubmit = function () {
    if (ta1.value === "") {
        result.style.color = "red";
        result.value = "Blank";
    } else {
        result.style.color = "blue";
        result.value = "Not Blank: '" + ta1.value + "'";
    }
    return false;
};