screenshot.js

function sleep(ms) {
  return new Promise(resolve => setTimeout(resolve, ms));
}

const puppeteer = require('puppeteer');
const Jimp = require('jimp');

const url = process.argv[2];
const jpgPath = process.argv[3];
const dimensionsType = process.argv[4];

const dimensions = {
  sixteenNine: {
    full: { width: 1920, height: 1080 },
    scaled: { width: 295, height: 166 },
  },
  twitter: {
    full: { width: 1080, height: 1080 },
    scaled: { width: 144, height: 144 },
  },
};

if (!dimensions[dimensionsType]) {
  throw `The dimensions type "${dimensionsType}" does not exist`;
}

(async () => {
  const browser = await puppeteer.launch();
  const page = await browser.newPage().catch(err => {
    console.log(err);
  });
  await page.setViewport(dimensions[dimensionsType].full);
  await getScreenshot(page, jpgPath);

  let counter = 0;
  let allOne = true;

  while (allOne && counter < 10) {
    allOne = await isAllOneColor(jpgPath);
    await getScreenshot(page, jpgPath);
    counter++;
  }

  await browser.close();

  await scaleScreenshot(jpgPath, dimensions[dimensionsType].scaled);
})();

async function scaleScreenshot(file, dimensions) {
  await Jimp.read(file, (err, screenshot) => {
    if (err) throw err;
    screenshot
      .resize(dimensions.width, dimensions.height) // resize
      .write(file); // save
  });
}

async function getScreenshot(page, file) {
  await page.goto(url).catch(err => {
    console.log(err);
  });
  await page
    .evaluate(() => {
      // dismiss github notice if it exists
      let button = document.querySelector('button[data-ga-click]');
      if (button) {
        button.click();
      }
    })
    .catch(err => {
      console.log('button click error', err);
    });
  await sleep(1000);
  return await page.screenshot({ path: jpgPath }).catch(err => {
    console.log('error', err);
  });
}

const pixelEqual = (first, second) => first.every((el, i) => second[i] === el);

async function isAllOneColor(file) {
  let allSame = true;
  let firstPixel = [];

  await Jimp.read(file).then(image => {
    const result = image.scan(
      0,
      0,
      image.bitmap.width,
      image.bitmap.height,
      function(x, y, idx) {
        var red = this.bitmap.data[idx + 0];
        var green = this.bitmap.data[idx + 1];
        var blue = this.bitmap.data[idx + 2];
        var alpha = this.bitmap.data[idx + 3];

        const currentPixel = [red, green, blue, alpha];

        if (!firstPixel.length) {
          firstPixel = currentPixel;
        } else if (!pixelEqual(firstPixel, currentPixel)) {
          allSame = false;
        }
      }
    );
  });

  return allSame;
}