How to convert a file to a byte array.
another way round of below one
let file = new File([myBlob], "name");
file need to convert into a byte stream
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1Do you work with image or not? Please provide the code you have already triedArtem Arkhipov– Artem Arkhipov2019-05-28 08:44:07 +00:00Commented May 28, 2019 at 8:44
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1Try this let byteArray = new Uint8Array(file)Dan Patil– Dan Patil2019-05-28 08:51:17 +00:00Commented May 28, 2019 at 8:51
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1 Answer
You can probably try to use FileReader API available in Browser.
let file = new File(...) // this could be from file input or other source
let fileReader = new FileReader();
fileReader.readAsArrayBuffer(file);
fileReader.onload = function(ev) {
const result = ev.target.result;
console.log(result); // here it is
}
According to this answer, if the result from readAsArrayBuffer will not work for you, you may need to convert it to the real byte[] using new Uint8Array. Here is extended version of the above code:
let file = new File(...) // this could be from file input or other source
let fileReader = new FileReader();
fileReader.readAsArrayBuffer(file);
fileReader.onload = function(ev) {
const array = new Uint8Array(ev.target.result);
const fileByteArray = [];
for (let i = 0; i < array.length; i++) {
fileByteArray.push(array[i]);
}
console.log(array); // here it is
}
And here is implementation wrapped in promise for comfortable usage:
function getByteArray(file) {
return new Promise(function(resolve, reject) {
fileReader.readAsArrayBuffer(file);
fileReader.onload = function(ev) {
const array = new Uint8Array(ev.target.result);
const fileByteArray = [];
for (let i = 0; i < array.length; i++) {
fileByteArray.push(array[i]);
}
resolve(array); // successful
}
fileReader.onerror = reject; // call reject if error
})
}
//usage
let file = new File(...)
getByteArray(file).then((byteArray) => {
// do whatever you need
console.log(byteArray);
})
P.S.
If for some reason you can not refer to ev.target, please try to use fileReader.result instead.
6 Comments
SSSS
this line show error. const result = ev.target.result; result is not property of target
Artem Arkhipov
It should work as event.target is documented in the documentation developer.mozilla.org/en-US/docs/Web/API/FileReader/onload
Artem Arkhipov
@SSSS see my updated answer. Try to use fileReader.result
Artem Arkhipov
@SSSS, so did the
fileReader.result solve the issue? P.S. if this answer solved your task, please, mark it as accepted. Thanks.SSSS
Yes. sure i do now.one last thing then how can I convert this byte array to string ??
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