CODEWITHSUNDEEP
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Cyker
Cyker

Reputation: 10994

JavaScript execution order in an HTML page

If I have an HTML page embedding several <script> tags, is there a guarantee that these script files will be executed in order they appear in the HTML file?

For example:

<script src="script1"></script>
<script src="script2"></script>

Is it guaranteed that script1 will always be executed before script2? If so, is it a cross-browser standard?

Upvotes: 1

Views: 1567

Answers (2)

enguerranws
enguerranws

Reputation: 8233

Those JS files will be parsed and interpreted by browser in the order you putted them : script1.js, then script2.js.

However, it doesn't garanty that the code in script1.js will be executed before script2.js : it depends on the code.

For example, let's consider you are listening to a DOM ready event in script2.js and you are listening to an image loaded event in script1.js. In this case, the code in script2.js will be parsed and interpreted after the code in script1.js, but it will be executed after.

Upvotes: 0

rsabir
rsabir

Reputation: 746

The answer is yes. The browser will download both scripts in parallel and execute them as soon as possible, maintaining their order. Here's a handfull article that treats this subject.

Upvotes: 2

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