Plot the PMF/PDF and CDF of common distributions. Compute mean, variance, tail probabilities, and quantiles. Pure JavaScript — no server, no plotting library.
PDFs are sampled at 400 points across a sensible domain for the chosen family. Tail probabilities use closed-form CDFs where available (normal → erf, exponential → 1−e−λx, etc.) and numerical integration (Simpson's rule) for gamma, beta, and log-normal. Quantiles use bisection on the CDF. Discrete distributions plot as stems with summed PMF for ranges. The math is approximate — good enough for visualization and back-of-envelope work, not for production statistical inference.