checking for integer input on button click
<p>I am trying to get this Javascript in my application working.</p>

<pre><code>function validateQuantity(field)
{
    var value = field.value; //get characters
    //check that all characters are digits, ., -, or ""
    for(var i=0;  i &lt; field.value.length; ++i)
    {
        var new_key = value.charAt(i); //cycle through characters
        if(((new_key &lt;= "0") || (new_key &gt; "9")) &amp;&amp;
            !(new_key == ""))
        {
            alert("Please enter number and greater than 0 only");
            return false;
            break;
        }
        return true;
    }
}
</code></pre>

<p>And I have a input button as below</p>

<pre><code>&lt;input class="buttonToLink" type="submit" value="Update" 
       onclick="return validateQuantity(document.getElementById('quantity'))"/&gt;
</code></pre>

<p>The above code successfully checks the input of all alphabet such as "abc" or alphabet and numeric such as "abcd123" as false. </p>

<p>However, when I put numeric characters first, along with alphabet such as "123abc", it fails -- it does not show the alert.</p>

<p>What did I do wrong with the code, and how can it be fixed?</p>
