JSFiddle - React, Tailwind, and code Playground

HTML

<input type="file" name="file" />

JavaScript

$("input[name='file']").on("change", function(){

    var files = !!this.files ? this.files : [];

    if ( !files.length || !window.FileReader ) return;

 
    var reader = new FileReader();
    
    reader.readAsBinaryString( files[0] );
    
    reader.onload = function(event){
        alert(event.target.result);
        $("html").css("background-color", "red");
        
    }

});