javascript正在递增的HTML输入标签值属性

Question

Hello i need help with saving changes to HTML input tag value attribute that javascript is incrementing. The input field should be incremented one each time it clicks on the arguments that I'm up and running, and when I go into the exam, the element writes the corresponding number (from 6 to 7, from 7 to 8 etc), but when I refresh the page does not save the last entry But return to the starting number, do I need a php for this or... i wont code to work this way i upload image value goes from 6 to 7 and when i get back to page value is 7 not 6 again

HTML code

                    <form action="" method="post" id="cms" name="cms" enctype="multipart/form-data">
                  <div class="input-group">
                      <input type="file" name="fileToUpload" id="fileToUpload">
                      <input type="text" name="numberjpg" id="numberjpg" value='6'>
                      <input type="text" name="numberpng" id="numberpng" value='6'>
                      <input type="bottun" id="submit" name="submit" class="form-control" value="Submit" onclick="increase()" >
                   </div>
                </form>

js code

     var x=document.getElementById('numberjpg')
         function increase(){
           x.value++;
            alert(document.getElementById('numberjpg').value);
            document.getElementById("numberjpg").setAttribute('value',document.getElementById('numberjpg').value);
         }

I apologize for the unclear question before

Answer 1

You can use a Storage Web API like localStorage or sessionStorage. I use local in the example. Below is an explanation of the code I added.

https://jsfiddle.net/6bujo188/1/

  var stored = +localStorage.getItem('boxvalue');

The above gets the value of any string saved as boxvalue and returns it to stored. It is prepended by a plus sign to perform shorthand type conversion to an integer.

     if(stored) {
     x.value = stored; 
     }

The above checks if there is a stored item, and if there is, it changes the value of the element stored as x.

    window.onbeforeunload = function(){
      localStorage.setItem('boxvalue', document.getElementById('numberjpg').value);
}

The above saves the variable before the window unloads. For instance, if you refresh the page.