How to upload form for txt and xlsx in javascript

How to upload form for txt and xlsx in javascript?

Source: StackOverflow.com

Question

I would like to make a form that allow user upload .txt and .xlsx file and write this file's contents in a div.I don't know if i should go server side to handle uploaded files.

Answer

You can read CSV or XLSX data with [Alasql][1] library. It uses [js-xlsx] library.

If you read data from server:

alasql('SELECT * FROM XLSX("data.xlsx", {headers:true})',[],function(data){
    // process data array
});

If you are reading data from the browser:

<script src="alasql.min.js"></script>
<script src="xlsx.core.min.js"></script>
<p>Select CSV file to read:</p>
<input id="readfile" type="file" onchange="loadFile(event)"/>
<script>
    function loadFile(event) {
        alasql('SELECT * FROM FILE(?,{headers:true})',[event],function(data){
	        // Process data here
        });
     }
</script>

Alasql automatically recognize file type by file extension.

You can try the working example of uploading data here.