Javascript怎么能找出出错在哪里呢？

Javascript实在太不newbie-friendly了，照着书上写了个计算器，对着看了N遍没有一个错误但就是运行不起来，也不报错，打开chrome的developer tool切换到script标签啥都看不到...

作为第一门语言学习是不是得换门语言啊，譬如Python？

<!DOCTYPE html>

<html>
<head>
<title></title>
<style type="text/css">
td {
border: 1px solid gray;
width: 50px;
}
#results {
height: 20px;
}
</style>
</head>
<body>
<table border="0" cellpadding="2" cellspacing="2">
<tr>
<td colspan="4" id="result"></td>
</tr>
<tr>
<td><a href="#">1</a></td>
<td><a href="#">2</a></td>
<td><a href="#">3</a></td>
<td><a href="#">+</a></td>
</tr>
<tr>
<td><a href="#">4</a></td>
<td><a href="#">5</a></td>
<td><a href="#">6</a></td>
<td><a href="#">-</a></td>
</tr>
<tr>
<td><a href="#">7</a></td>
<td><a href="#">8</a></td>
<td><a href="#">9</a></td>
<td><a href="#">*</a></td>
</tr>
<tr>
<td><a href="#">Clear</a></td>
<td><a href="#">0</a></td>
<td><a href="#">=</a></td>
<td><a href="#">/</a></td>
</tr>
</table>
<script type="text/javascr ipt">
//using early dom event handlers
function addDigit(digit){
var resultField = document.getElementById("result");
resultField.innerHTML += digit;
return false;
}
function calculate(){
var resultField = document.getElementById("result");
resultField.innerHTML = eval(resultField.innerHTML);
return false;
}
function clear(){
var resultField = document.getElementById("result");
resultField.innerHTML = "";
return false;
}
function getHandlerFunction(innerHTML){
return function(){
addDigit(innerHTML);
return false;
};
}

onload = function() {
var links = document.getElementsByTagName("a");
var length = links.length;

for (var i = 0; i < length; i ++) {
var link = links[i];
var innerHTML = link.innerHTML;

switch(innerHTML) {
case "Clear":
link.onclick = clear;
break;
case "=":
link.onclick = calculate;
break;
default:
link.onclick = getHandlerFunction(innerHTML);
break;
}
}
};

</script>
</body>
</html>