javascript - How to concatenate files which are in ? -

i have multiple html files in have usemin comment this:

html 1

<!-- build:js scripts/vendor1.js -->   <script src="scripts/script1.js"></script>   <script src="scripts/script2.js"></script> <!-- endbuild -->

html 2

<!-- build:js scripts/vendor2.js -->   <script src="scripts/script1.js"></script>   <script src="scripts/script2.js"></script> <!-- endbuild -->

html 3

<!-- build:js scripts/vendor3.js -->   <script src="scripts/script1.js"></script>   <script src="scripts/script2.js"></script> <!-- endbuild -->

how concatenate files between build:js via gruntfile? , create vendor1.js, vendor2.js , vendor3.js

thanks in advance help.

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