Is it true that first line of Javascript will be executed only after all script tags with src attribute are downloaded and evaluated?

By first 开发者_运维问答line of Javascript I meant the JS code inside tags with no "src" attribute.

By right it will be evaluated top down.

Read more about it from my previous answer: Load and execution sequence of a web page?

Let me explain here:

<script type="text/javascript">
  alert(jQuery); // alerts jQuery's namespace
</script>
<script type="text/javascript" src="jquery.js"></script>

The result is alerting undefined.

<script type="text/javascript" src="jquery.js"></script>
<script type="text/javascript">
  alert(jQuery); // alerts jQuery's namespace
</script>

The result is alerting a object/function where defined.

The scripts are executed in the order they are listed in the html. It does not matter if they are inline JavaScript (within <script> tags) or if loaded as external scripts (<script src="xx.js">).