How can i javascript in mustasche

I want to use javascript inside the mustache template. (test.mustache)

https://test.com/?lang=en

<script>
let query = window.location.search;
console.log(query);
</script>

I got ?lang=en with the above code.

{{#cats}}
<a href="{{link}}" class="ui label-lsc" style="background-color: {{wpsc_cat_bg_color}}; color: {{wpsc_cat_color}};">{{{value}}}</a>
{{/cats}}

i in this code
I want to append ?lang=en after {{link}}.

Is there any way?