Can someone give me an example of using the FileReader API go get contents of a file in chrome?
It seems to be returning undefined
for me.
<!doctype html>
<html>
<script>
function handle_files(files) {
console.log(files)
reader = new FileReader()
ret = []
for (i = 0; i < files.length; i++) {
file = files[i]
console.log(file)
text = reader.readAsText(file) //readAsdataURL
console.log(text) //undefined
ret.push(text)
}
console.log(ret) // [undefined]
}
</script>
<body>
FileReader Test
<input type="file" onchange="handle_files(this.files)">
</body>
</html>
My problem was that I assumed FileReader was sychronous. Here is the right way to do it. If you are on chrome, this code has to be running on a server (localhost or on a site). It won't work with a local file.
<!doctype html>
<html>
<script>
function handle_files(files) {
for (i = 0; i < files.length; i++) {
file = files[i]
console.log(file)
var reader = new FileReader()
ret = []
reader.onload = function(e) {
console.log(e.target.result)
}
reader.onerror = function(stuff) {
console.log("error", stuff)
console.log (stuff.getMessage())
}
reader.readAsText(file) //readAsdataURL
}
}
</script>
<body>
FileReader that works!
<input type="file" multiple onchange="handle_files(this.files)">
</body>
</html>