i want to use javascript for my conditional statement

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  • simon2x1
    New Member
    • Dec 2008
    • 123
    #1

    i want to use javascript for my conditional statement

    i have an upload form that upload image into a folder i want the upload field not to post a blank field and also not to allow any image which is not gif, jpeg and png not to be uploaded how can i do these with javascript. the code below is my upload form code

    Code:
     <form name="the_form" id="the_form" method="POST" action="uploaded.php" enctype="multipart/form-data">
       <input name="images[]" type="file"  id="field_1" > 
     <input type="hidden" name="MAX_FILE_SIZE" value="2000000">
 <input name="submit" type="submit" value="submit" />
 </form>
    Tags: None
    • acoder
      Recognized Expert MVP
      • Nov 2006
      • 16032
      #2
      I assume you know how to add form validation. Add to that a check on the form file field, if your browser gives access to the field. You can access the value as follows:
      Code:
      document.getElementById("the_form").elements["images[]"].value
      With the image types, you can only check the extension.

        Comment

        • simon2x1
          New Member
          • Dec 2008
          • 123
          #3
          i am a beginner in java script, i dnt know how to validate a form. pls i would appreciate it if u would help with my "upload field so that not to post a blank field and also not to allow any image which is not gif, jpeg and png not to be uploaded "

            Comment

            • acoder
              Recognized Expert MVP
              • Nov 2006
              • 16032
              #4
              The basic components for form validation:
              1. an onsubmit handler:
              Code:
              <form ... onsubmit="return validateForm()">
              2. A validation function:
              Code:
              function validateForm(form) {
...
}
              3. return false for failures:
              Code:
              if (elem.value.length == 0) {
    alert("Error!");
    elem.focus();
    return false;
}
              4. If validation passes completely, return true:
              Code:
              // validate all fields
    ...
    // no more validation left:
    return true
}//end of function

                Comment

                • simon2x1
                  New Member
                  • Dec 2008
                  • 123
                  #5
                  i have added the validation to my code below it sill did not work pls i appreciate it if you help me fix this problem don't forget i want the upload field not to post a blank field and also not to allow any image which is not gif, jpeg and png not to be uploaded

                  Code:
                  <html>
<head>
<title></title>
<head>
<script language="JavaScript">
function validateForm(form) {

  if (elem.value.length == 0) {
        alert("Error!");
        elem.focus();
        return false;
    }else{
document.getElementById("the_form").elements["images[]"].value
	}
}
</script>

<body>
<form  method="POST" action="uploaded.php" enctype="multipart/form-data" onsubmit="return validateForm()">
<input name="images[]" type="file"  id="field_1" > 
<input type="hidden" name="MAX_FILE_SIZE" value="2000000">
<input name="submit" type="submit" value="submit" />
 </form>
<body>
</html>

                    Comment

                    • simon2x1
                      New Member
                      • Dec 2008
                      • 123
                      #6
                      still need help with the validation

                      i have added the validation to my code below it sill did not work pls i appreciate it if you help me fix this problem don't forget i want the upload field not to post a blank field and also not to allow any image which is not gif, jpeg and png not to be uploaded

                      Code:
                      <html>
<head>
<title></title>
<head>
<script language="JavaScript">
function validateForm(form) {

  if (elem.value.length == 0) {
        alert("Error!");
        elem.focus();
        return false;
    }else{
document.getElementById("the_form").elements["images[]"].value
	}
}
</script>

<body>
<form  method="POST" action="uploaded.php" enctype="multipart/form-data" onsubmit="return validateForm()">
<input name="images[]" type="file"  id="field_1" > 
<input type="hidden" name="MAX_FILE_SIZE" value="2000000">
<input name="submit" type="submit" value="submit" />
 </form>
<body>
</html>

                        Comment

                        • acoder
                          Recognized Expert MVP
                          • Nov 2006
                          • 16032
                          #7
                          "elem" on line 8 has to refer to an element, otherwise you will get an error. You can use the id "field_1":
                          Code:
                          var elem = document.getElementById("field_1");

                            Comment

                            • Bassem
                              Contributor
                              • Dec 2008
                              • 344
                              #8
                              Line 13, You got the value of an element but you don't use it.
                              At the end of the validation function you didn't return true.

                                Comment

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