how to make radio button checked on condition based?

I want to make radio button checked on condition based. Like when index=>4, button 4 should be checked. My HTML code is like that:

<input id="rating5" type="radio" name="rating" value="5">
<label for="rating5">5</label>
<input id="rating4" type="radio" name="rating" value="4">
<label for="rating4">4</label>
<input id="rating3" type="radio" name="rating" value="3">
<label for="rating3">3</label>
<input id="rating2" type="radio" name="rating" value="2" >
<label for="rating2">2</label>
<input id="rating1" type="radio" name="rating" value="1">
<label for="rating1">1</label>

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