remove-unused-imports.js

#!/usr/local/bin/node
// From a gist of Jinjor: https://gist.github.com/jinjor/cce51986afa422a3e38befebe091ead2
const fs = require("fs");
const childProcess = require("child_process");

childProcess.exec("./node_modules/.bin/elm-analyse", (e, out) => {
    let file;
    let unusedImports = {};
    let unusedAliases = {};
    for (let line of out.split("\n")) {
        if (line.startsWith("-")) {
            file = line.slice(2);
            continue;
        }
        const matched1 = line.match(
            /.*Unused import `.*at.*\(\((\d+),(\d+)\),\((\d+),(\d+)\)\)/
        );
        if (matched1) {
            if (!unusedImports[file]) {
                unusedImports[file] = [];
            }
            const [start, end] = [+matched1[1], +matched1[3]];
            unusedImports[file].push({
                start,
                end
            });
        }
        const matched2 = line.match(
            /.*Unused import alias `.*at.*\(\((\d+),(\d+)\),\((\d+),(\d+)\)\)/
        );
        if (matched2) {
            if (!unusedAliases[file]) {
                unusedAliases[file] = [];
            }
            const [start, end] = [+matched2[1], +matched2[3]];
            unusedAliases[file].push({
                start,
                end
            });
        }
    }
    for (let file in unusedImports) {
        const contentArray = fs.readFileSync(file, "utf8").split("\n");
        const ranges = unusedImports[file];
        ranges.forEach(({
            start,
            end
        }) => {
            for (let i = start - 1; i < end; i++) {
                console.log("Unused Import:", contentArray[i]);
                contentArray[i] = null;
            }
        });
        const content = contentArray.filter(s => s !== null).join("\n");
        fs.writeFileSync(file, content);
    }
    for (let file in unusedAliases) {
        const contentArray = fs.readFileSync(file, "utf8").split("\n");
        const ranges = unusedAliases[file];
        ranges.forEach(({
            start,
            end
        }) => {
            for (let i = start - 1; i < end; i++) {
                console.log("Unused Alias:", contentArray[i]);
                contentArray[i] = contentArray[i].replace(/ as ([^ ]*)/, "");
            }
        });
        const content = contentArray.filter(s => s !== null).join("\n");
        fs.writeFileSync(file, content);
    }
});