This is a Node.js script to check if it is an animated GIF.

is-animated-gif.js

(async() => {
  const gifFrames = require('gif-frames');
  const fs = require('fs');
  const path = require('path');
  const gifPath = process.argv[2];

  if(!gifPath) {
    console.log('Please provide an gif file as an argument');
    process.exit(1);
  }

  const gifAbsPath = path.resolve(gifPath);
  if(!fs.existsSync(gifAbsPath)) {
    console.log('The provided gif file does not exists');
    process.exit(1);
  }

  gifFrames({ url: gifAbsPath, frames: 'all', outputType: 'png', cumulative: true })
    .then(function (frameData) {
        if (frameData.length > 1) {
            console.log('This GIF is animated.');
        } else {
            console.log('This GIF is not animated.');
        }
    })
    .catch(function (err) {
        console.error('An error occurred: ', err);
    });
})()