JavaScript File API, Blobs and FileReaders Read file as string

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Make sure to have a file input on your page:

<input type="file" id="upload">

Then in JavaScript:

document.getElementById('upload').addEventListener('change', readFileAsString)
function readFileAsString() {
    var files = this.files;
    if (files.length === 0) {
        console.log('No file is selected');

    var reader = new FileReader();
    reader.onload = function(event) {
        console.log('File content:',;

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