You need to break it down:
<script type="text/javascript" src="https://ajax.googleapis.com/ajax/libs/jquery/1.5.0/jquery.min.js">
$(document).ready(function() {
$("a").click(function() {
alert("Hello world!");
});
});
</script>
... into two script elements:
<script type="text/javascript" src="https://ajax.googleapis.com/ajax/libs/jquery/1.5.0/jquery.min.js"></script>
<script type="text/javascript">
$(document).ready(function() {
$("a").click(function() {
alert("Hello world!");
});
});
</script>
In the passage you indicated, the code in the element <script>will not be evaluated, because the browser only evaluates the content from the attribute srcand ignores everything else.
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