新标签页始终打开，即使是普通表单也可以提交

Question

I'm using two submit buttons, one for page open in new tab (preview) and another for ordinary form submission (publish).

My issues are:

1. If I click preview button and open in tab, after that publish button click again NEW TAB will open
2. After refresh only publish button submit usually.

<form method="post" name="form">
  Name : <br> <input type="text" name="name"/><br />
  Address : <br> <input type="text" name="address"/><br />
  <input name="publish" type="submit" value="Submit" onclick="action='proccess.php?action=submit';"> 
  <input type="submit" value="preview" onclick='formpreview(this.form)'/>
</form>

<script>
  function formpreview(form) 
    form.target = '_blank';
    form.action = 'preview.php';
    form.submit();
  }
</script>

Answer 1

Remove

form.target = '_blank';

target="_blank" is given when you want to open webpages in new tab.

Edit

<form method="post" name="form" action="proccess.php?action=submit">
  Name : <br> <input type="text" name="name"/><br />
  Address : <br> <input type="text" name="address"/><br />
  <button type="submit" value="Submit" name="publish" > Publish </button>
  <button type="button" value="preview" onclick='formpreview(this.form)'>Preview</button
</form>

Answer 2

you can check button values, and then submit form with you conditions,

<form method="post" name="form">
  Name : <br> <input type="text" name="name"/><br />
  Address : <br> <input type="text" name="address"/><br />
  <input name="submit" type="submit" value="Submit" onclick="formpreview(this.form,this)"> 
  <input type="submit" value="preview" onclick='formpreview(this.form,this)'/>
</form>

<script>
  function formpreview(form,btn) {
    alert(btn.value);
    /*form.target='_blank';
    form.action='preview.php';
    form.submit();*/
    if(btn.value=="preview"){
        alert(btn.value);
        form.target='_blank';
        form.action='preview.php';
        form.submit();
    }
    if(btn.value=="Submit"){
        alert(btn.value);
         form.target='_self';
         form.action='proccess.php?action=submit';
         form.submit();
    }

  }
</script>