//selectedFileData is array of selected video file from input
const data = new FormData();
for (let i = 0; i < selectedFileData.length; i++) {
data.append("file", selectedFileData[i]);
data.append("fileSize", convertSize(selectedFileData[i].size, "MB"))
data.append("videoDuration",(i want to append video duration of video from here));
}
You can use the modern browser's URL API's URL.createObjectURL() with an non appended video element to load the content of your file.
const data = new FormData();
for (let i = 0; i < selectedFileData.length; i++) {
let videoElem = document.createElement('video');
videoElm.preload = `metadata`;
video.onloadedmetadata = function() {
window.URL.revokeObjectURL(video.src);
let duration = video.duration;
data.append("videoDuration", duration);
}
video.src = URL.createObjectURL(files[0]);;
}