call PHP function inside JS

Question

I want to call a php function inside a JS function, my php function uses an input as param and push the returned value in the : index.html :

<input type="text" name="my_value">
<button type="button" name="confirm" onclick="validate()">Submit</button>

my_script.JS:

    function validate() {
        var errors = [];
        //here I want to call check function using the input my_value
    }

test.php :

function check($my_value){
   //some long test on $my_value{
        return "valid";
    }else{
        return "not valid";
    }
}

How can I call it in my validate JS function?