parseCoverage.js

import * as fs from "fs";

const coverage = JSON.parse(
    fs.readFileSync("coverage/coverage-final.json", "utf-8")
);

const output = Object.values(coverage).map((x) => {
    const path = x.path;
    const totalStatements = Object.keys(x.statementMap).length;
    const coveredStatements = Object.entries(x.s).filter(
        ([statementId, callCount]) => callCount > 0
    ).length;
    const uncoveredStatements = totalStatements - coveredStatements;

    return {
        path,
        totalStatements,
        coveredStatements,
        uncoveredStatements,
    };
});

const fileHandle = fs.openSync("./something.csv", "w");
try {
    fs.writeSync(
        fileHandle,
        "Path,Total Statements,Covered Statements,Uncovered Statements\n"
    );
    output.forEach((x) => {
        fs.writeSync(
            fileHandle,
            [
                x.path,
                x.totalStatements,
                x.coveredStatements,
                x.uncoveredStatements,
            ].join(",") + "\n"
        );
    });
} finally {
    fs.closeSync(fileHandle);
}