JSFiddle - React, Tailwind, and code Playground

by Harish Singh

HTML

<input type="file" name="file" id="fileid">

JavaScript

document.getElementById('fileid').addEventListener('change', checkFile, false);

function checkFile(e) {
    var file_list = e.target.files;
    for (var i = 0, file; file = file_list[i]; i++) {
        var fileExtension = file.name.split('.')[file.name.split('.').length - 1].toLowerCase();
        var iConvert = (file.size / 1024).toFixed(2);

        txt = "File type : " +fileExtension + "\n";
        if(file.size > (1024 * 1024)){
            txt += "Size: " + (file.size / (1024*1024)).toFixed(2) + " MB \n";
        } else {
        txt += "Size: " + (file.size / 1024).toFixed(2) + " KB \n";
        }
        alert(txt);
    }
}