JSFiddle - React, Tailwind, and code Playground

HTML

<title>Previzualizare test</title>
<body>
<div id="center2">
  <div id="forme">
		
 <form method="post" action="edit_posts.php?editare=2" enctype="multipart/form-data" id="mainform">
    
	 Imagine 1:<br>
   	 <input type="file" name="img1" id="img1"><br>
	 	 <br><br>     
	Imagine 2 :<br>
     <input type="file" name="img2" id="img2"><br>
		 <br>
     Imagine 3 :<br>
     <input type="file" name="img3" id="img3"><br>
		 <br>
     Imagine 4 :<br>
     <input type="file" name="img4" id="img4"><br>
		 <br>
	 Imagine 5 :<br>
     <input type="file" name="img5" id="img5"><br>
		 <br>
     Imagine 6 :<br>
     <input type="file" name="img6" id="img6"><br>
		 <br>
     Imagine 7 :<br>
     <input type="file" name="img7" id="img7"><br>
		 <br>
     Imagine 8 :<br>
     <input type="file" name="img8" id="img8"><br>
		 <br>
     Imagine 9 :<br>
     <input type="file" name="img9" id="img9"><br>
		 <br>
     Imagine 10 :<br>
     <input type="file" name="img10" id="img10"><br>
		 <br>
     Imagine 11 :<br>
     <input type="file" name="img11" id="img11"><br>
		 <br>
     Imagine 12 :<br>
     <input type="file" name="img12" id="img12"><br>
		 <br>
     Imagine 13 :<br>
     <input type="file" name="img13" id="img13"><br>
		 <br>
     Imagine 14 :<br>
     <input type="file" name="img14" id="img14"><br>
		 <br>
     Imagine 15 :<br>
     <input type="file" name="img15" id="img15"><br>
		 <br>
Continut:<br>
   	 <textarea id="insert" name="content" placeholder="Introduceti date despre articol" rows="25" cols="50"><p>1. Cautare secventiala
<br>
2. Cautare binara
<br>
<img src="" id="img3">
3. Interclasare 
<br>
4. Metode de sortare (Interschimbare, Metoda bulelor)</p><img src="" id="img1">
<img src="" id="img2">;</textarea><br> 
	 <br />
	 Preview:
   	 <br />
   	 <input type="checkbox" id="previz" />Preview
   	 <br />
   	 <div class="arata" style="display: none;"></div>
   	 <br />
 </form>
    </div>
	   <div id="vezi">
	   <hr>
   <h1></h1>
   <p></p>
   <hr>
          ...

JavaScript

var j;
    var i="1"; 
	var countd;
	var counti;
	var titlei = "title";
	var continuti = "insert";
	var cuvci = "keywords";
	var autori = "author";
	var continut = $("#"+continuti).val();
	var titlu = $("input[name='"+titlei+"']").val();
	var cuvc = $("input[name='"+cuvci+"']").val();
	var autor = $("input[name='"+autori+"']").val();
	var vt = "#center2 #forme";
	var vc =  vt + " #previz";
	//De tipul form#idformular
	var numeformular= "form#mainform";
	// principdiv trebuie sa contina un spatiu la final !!!
	var principdiv = "#center2 #vezi ";
	var h1titlu = "h1";
	var pcontinut= "p";

    $(vc).change(function(){
	continut = $("#"+continuti).val();

	if(this.checked){
	
	//Continut
	if(continut != '' && continut != undefined){
	$(principdiv+pcontinut).html(continut);
	
	}
	}
	
	});
 

 	  
   function readURL(input) {
        if (input.files && input.files[0]) {
            var reader = new FileReader();
            
            reader.onload = function (e) {
			    console.log(e.target.result+" , "+i);
                $(principdiv+'#img'+i).attr('src', e.target.result);
            }
            
            reader.readAsDataURL(input.files[0]);
        }
	}

    
    $("#center2 #forme form#mainform #img"+i).change(function(){
        readURL(this);
		i++;
    });