add text in input field with jquery code example

Example 1: jquery add text to textbox

jquery add text to textbox 
$("#id").val(whatever you want to display inside the textbox)

Example 2: assign input text value jquery

<?= $this->Form->input('number_six', array(
     'label' => false,
     'class' => 'form-control number_six',
     'maxlength' => "1" ,
     'oninput' => "this.value=this.value.replace(/[^0-9]/g,'');"
   ));?>

$(".number_six").val("");