JSFiddle - React, Tailwind, and code Playground

by Alex Alex

HTML

<input type="file">

JavaScript

var input = document.getElementsByTagName('input')[0];

input.addEventListener('change', function () {
    var file = this.files[0];
    [
        'readAsDataURL',
        'readAsBinaryString',
        'readAsArrayBuffer'
    ].forEach(function (method) {
        var reader = new FileReader();
        reader.onload = function (method, e) {
            var result = e.target.result;
            console.log(method, result.length || result.byteLength);
        }.bind(null, method)
        reader[method](file);
    });
});