Calculate a smoothed upload ETA

Estimate remaining upload time with an EWMA rate that resists unstable progress jumps.

MediumJavaScript Algorithms

50 min0% acceptance

Description

Implement calculateSmoothedUploadEta(samples, totalBytes, alpha = 0.5). Validate strictly increasing sample times and nondecreasing loaded bytes, calculate instantaneous byte rates, fold them into an exponentially weighted moving average whose newest rate has weight alpha, and return the ceiling of remaining seconds.

Requirements

Export a callable calculateSmoothedUploadEta function from src/App.js.
Fold interval byte rates into an EWMA with the newest rate weighted by alpha.
Return Math.ceil(remainingBytes / smoothedBytesPerSecond).
Use all valid intervals in order so short-lived rate changes do not replace the estimate outright.
Return zero when the latest loaded byte count equals totalBytes.
Return null when fewer than two valid samples or no positive transfer rate are available.
Throw RangeError for invalid totals, alpha, byte counts, regressions, or non-increasing timestamps.
Do not mutate or reorder the sample array or its objects.

Smoothed intervals

Input

[{loaded:0,timeMs:0},{loaded:100,timeMs:1000},{loaded:300,timeMs:2000}], total 700, alpha 0.5

Expected output

Explanation

Rates of 100 and 200 bytes/second smooth to 150; 400 bytes remain, so the ceiling is three seconds.

Insufficient history

Input

One valid sample

Expected output

null

Explanation

At least one elapsed interval is required to estimate a rate.

Constraints

alpha must be greater than zero and at most one
loaded values are finite bytes between zero and totalBytes
timeMs values must increase strictly

Hints

Hint 1

Convert each byte delta and millisecond delta into bytes per second.

Hint 2

Seed the EWMA with the first interval rate, then combine later rates using alpha.

Hint 3

Validate the full sequence before returning early for completion.

JavaScriptEWMAprogress