我的HTML：

<form name="basicText" id="basicText" action="">
<p>Enter any ol' integer: 
<input type="text" id="inputBox" name="inputBox" size="14"/>    
<input value = "Next...?" type="submit" id="mySubmitBtn" name="mySubmitBtn"/>
</p>
</form>
<script src="js/w1bscript.js" type="text/javascript"></script>

另请注意,外部javascript文件在末尾添加,因此所有元素都可以加载(现在不用担心onload).

JavaScript：

var myButton1 = document.getElementById("mySubmitBtn");
var myForm1 = document.getElementById("basicText");
var myTextBox = myForm1.inputBox;

function submitPress() {
 if(myTextBox.value.length == 0) {
    alert("You didn't enter anything! Once more time,with feeling...")
    basicText.focus();
    basicText.select();
 } else if(/\s/.test(myTextBox.value)) {
    alert("Eh... No spaces. Just integers. Try again...");
    basicText.focus();
    basicText.select();
  } else if (isNaN(myTextBox.value)==true) {
    alert("Eh... Gonna need you to enter ONLY digits this time. kthnx.");
    basicText.focus();
    basicText.select();
 } else {
    // The textBox isn't empty,and there's no spaces. Good.
    alert("you've passed the test!")
  }
}
myButton1.addEventListener('click',submitPress,false);

当我输入错误的输入时,逻辑工作,但无论我使用什么浏览器,光标都不会聚焦回文本框.

小提琴：http://jsfiddle.net/2CNeG/

谢谢,
唐