promise-file-reader

Wraps FileReader in a Promise

Install

npm install --save promise-file-reader

Usage

Basic syntax

1const PromiseFileReader = require('promise-file-reader');
2
3PromiseFileReader.readAsDataURL(fileData)
4  .then(newImage)
5  .catch(err => console.error(err));

Example: file input

1import {readAsDataURL, readAsText, readAsArrayBuffer} from 'promise-file-reader';
2
3function newImage(imageDataUrl) {
4  ...
5}
6function newTextFile(text) {
7  ...
8}
9function loadedArrayBuffer(arrayBuffer) {
10  ...
11}
12
13// e.g. <input id="file-input" type="file" />
14const fileInput = document.getElementById('file-input');
15fileInput.addEventListener("change", handleFiles, false);
16function handleFiles(event) {
17  const fileMetaData =  event.target.files[0];
18
19  if(fileMetaData) {
20    if (/^image/.test(fileMetaData.type)) {
21      readAsDataURL(fileMetaData)
22      .then(newImage)
23      .catch(err => console.error(err));
24    } else {
25      readAsText(fileMetaData)
26      .then(newTextFile)
27      .catch(err => console.error(err));
28    }
29    // or
30    readAsArrayBuffer(fileMetaData)
31      .then(loadedArrayBuffer)
32      .catch(err => console.error(err));
33  }
34}