$supp = array('À', 'Á', 'Â');
$replace = array('A', 'A', 'A');
str_replace($supp, $replace, $str);

str_replace("é", "e", str_replace("É", "E", str_replace("è", "e", str_replace("È", "E", q4_SQ001))))

<script type="text/javascript" charset="utf-8">  
  $(document).ready(function() {
 
    // Identify some elements
    var thisQuestion = $('#question{QID}');
    var input1 = $('li.question-item:eq(0) input.text', thisQuestion);
    var input2 = $('li.question-item:eq(1) input.text', thisQuestion);
 
    // Hide the second input
    //$('li.question-item:eq(1)', thisQuestion).hide();
 
    // Listener on the first input
    input1.on('keyup', function(e){
      repSpecChars();
    });
    input1.on('paste', function(e){
      setTimeout(function () {
        repSpecChars();
      }, 100);
    });
 
    // A function to replace special characters
    function repSpecChars(str) {    
      // The character arrays (must be same length
      var specialChars = ["ù", "Ù", "û", "Û", "à", "Â", "ç", "Ç", "é", "É", "è", "È", "ê", "Ê", "î", "Î", "ô", "Ô"];
      var nonSpecialChars = ["u", "U", "u", "U", "a", "A", "c", "C", "e", "E", "e", "E", "e", "E", "i", "I", "o", "O"];
 
      var input1Val = input1.val().toString();
 
      $(specialChars).each(function(i){
        input1Val = input1Val.replace(
          new RegExp(specialChars[i], 'g'),
          nonSpecialChars[i]
        );
      });
      input2.val(input1Val);
    }
    });
</script>

str_replace(['À', 'Á', 'Â'], ['A', 'A', 'A'], QUESTION);