als-statistics/lib/descriptive/slope-by-index.js

Modular JS statistics toolkit for Node.js and the browser: descriptive stats, correlations (Pearson/Spearman/Kendall), t-tests & ANOVA (Student/Welch), reliability (Cronbach’s alpha), regression (linear/logistic), clustering (DBSCAN/HDBSCAN), and table/co

function slopeByIndex(arr) {
    if (arr.length < 2) return 0;
    const firstIndex = 0;
    const lastIndex = arr.length - 1;
    const deltaY = arr[lastIndex] - arr[firstIndex];
    const deltaX = lastIndex - firstIndex;
    return deltaY / deltaX;
}

export default slopeByIndex