How to read(in), print(out) value to text file by Javascript?

Here is a sample code for saving the data as a text file and loading in the HTML. You can modify this code and use as per your convenience.

function saveTextAsFile()
{
    var textToSave = document.getElementById("inputTextToSave").value;
    var textToSaveAsBlob = new Blob([textToSave], {type:"text/plain"});
    var textToSaveAsURL = window.URL.createObjectURL(textToSaveAsBlob);
    var fileNameToSaveAs = document.getElementById("inputFileNameToSaveAs").value;
    var downloadLink = document.createElement("a");
    downloadLink.download = fileNameToSaveAs;
    downloadLink.innerHTML = "Download File";
    downloadLink.href = textToSaveAsURL;
    downloadLink.onclick = destroyClickedElement;
    downloadLink.style.display = "none";
    document.body.appendChild(downloadLink);
    downloadLink.click();
}
function destroyClickedElement(event)
{
    document.body.removeChild(event.target);
}
function loadFileAsText()
{
    var fileToLoad = document.getElementById("fileToLoad").files[0];
    var fileReader = new FileReader();
    fileReader.onload = function(fileLoadedEvent) 
    {
        var textFromFileLoaded = fileLoadedEvent.target.result;
        document.getElementById("inputTextToSave").value = textFromFileLoaded;
    };
    fileReader.readAsText(fileToLoad, "UTF-8");
}