When to use it

This suits numbers that rise and fall over time, such as revenue, user counts or page views. Instead of screen-recording a spreadsheet chart, you get the lines growing as a video file. The data is two parts: timeline (the list of periods) and series (name, color and values).

For a period whose value is unknown, put null at that position in values. The number of entries in values must match timeline; if it does not, a message appears when you apply the JSON. Use "Save JSON" to keep the data as a file, and "Load JSON" to read it back next time.

How the length is decided

The total time is the zoom-in intro, plus the line drawing time, plus the hold at the end. The seek bar shows the position within that total. The playback speed (0.25x to 3x) only affects what you watch on screen; the recorded video keeps its own length.

How the Y axis moves

yAxis.mode in the JSON takes three values. With grow, the upper limit follows the lines as they advance, which makes the rise feel stronger. fixed pins the axis to max, and auto derives one fixed value from all the data. startMax is the starting limit for grow, headroom is the space kept above the highest value, and smooth controls how gently the axis follows.

Adjusting the look

The grid, the legend, the value label at the tip and the actual data points can each be turned off. If the text looks small, raise the "Title", "Axis and period labels", "Value at the line tip" and "Large current value" sliders. Neon glow, tip trail and particles are decorative, so switch them off for a calmer chart. With many series, "First series only" lets you check them one at a time.

Only the canvas is recorded, so the settings panel and the buttons never appear in the video. The safe area guide is a preview aid and is not recorded either. Recording uses MediaRecorder and captureStream, so a recent Chrome or Edge is recommended.