JSFiddle - React, Tailwind, and code Playground

HTML

<body>
<input id="countspr1" name="checkcountsp[]" type="text" maxlength="2" size="1" value="" > 
<input type="checkbox" id="spr1" name="checksp[]" value="Товар 1">Товар 1
<br>
<input id="countspr2" name="checkcountsp[]" type="text" maxlength="2" size="1" value=""/> 
<input type="checkbox" id="spr2" name="checksp[]" value="Товар 2">Товар 2
<br>
<input id="countspr3" name="checkcountsp[]" type="text" maxlength="2" size="1" value=""/> 
<input type="checkbox" id="spr3" name="checksp[]" value="Товар 3">Товар 3
</body>

JavaScript

$("input[name='checkcountsp[]']").hide();
$("input[name='checksp[]']").change(function() {
    var counch = $(this).prev();
    if(this.checked){
        $(counch).show();
		counch.focus();
		counch.value = 1;
	}
	else{
        $(counch).hide();        
		counch.value = '' ;
	}
})