I used the below code to upload multiple files. Its working absolutely fine but as i need to check that the file which i am uploading is duplicate or not, i am facing one problem in that. I created one function called checkDuplicate for that and calling it inside the function. But the problem is that the for loop is looping double the size of the array. I don’t know why it is so. Please kindly help me if anyone has any idea.
Here is the Javascript
<script type="text/javascript">
function MultiSelector(list_target, max) {
this.list_target = list_target;
this.count = 0;
this.id = 0;
if (max) {
this.max = max;
} else {
this.max = -1;
};
this.addElement = function(element) {
if (element.tagName == 'INPUT' && element.type == 'file') {
element.name = 'file_' + this.id++;
element.multi_selector = this;
element.onchange = function() {
var new_element = document.createElement('input');
new_element.type = 'file';
this.parentNode.insertBefore(new_element, this);
this.multi_selector.addElement(new_element);
this.multi_selector.addListRow(this);
this.style.position = 'absolute';
this.style.left = '-1000px';
};
if (this.max != -1 && this.count >= this.max) {
element.disabled = true;
}
;
this.count++;
this.current_element = element;
}
else {
alert('Error: not a file input element');
}
;
};
this.addListRow = function(element) {
var new_row = document.createElement('div');
var new_row_button = document.createElement('img');
new_row_button.setAttribute("src","<%=request.getContextPath()%>/images/deletei.gif");
new_row_button.onclick = function() {
this.parentNode.element.parentNode.removeChild(this.parentNode.element);
this.parentNode.parentNode.removeChild(this.parentNode);
this.parentNode.element.multi_selector.count--;
this.parentNode.element.multi_selector.current_element.disabled = false;
return false;
};
if(checkDuplicate(element)) {
new_row.element = element;
new_row.innerHTML = element.value + " ";
new_row.appendChild(new_row_button);
this.list_target.appendChild(new_row);
}
};
};
function checkDuplicate(element) {
var arr = new Array();
var i = 0,dup=0;
//alert(new_row.element = element.value);
if(dup==0) {
arr[i++] = element.value;
dup=1;
}
alert("Length ==> "+ arr.length);
for ( var j = 0; j < arr.length; j++) {
alert("Name ==> " + arr[j]);
if(arr[j] == element.value && j>=1) {
alert("Duplicate");
} else {
alert("Not Duplicate");
arr[i++] = element.value;
}
}
}
</script>
Here is the HTML
<body>
<!-- This is the form -->
<form enctype="multipart/form-data" action=""method="post">
<input id="my_file_element" type="file" name="file_1">
<input type="submit">
<br/>
<br/>
Files:
<!-- This is where the output will appear -->
<div id="files_list"></div>
</form>
<script>
var multi_selector = new MultiSelector(document
.getElementById('files_list'), 15);
multi_selector.addElement(document.getElementById('my_file_element'));
</script>
</body>
</html>
because you have the arr[i++] = element.value; in the last line, and j < arr.length in the for, so every time the array.lenght gets bigger and bigger.
change the for line to these two lines: