getColorAmout.js

const getPixels = require("get-pixels");

//1px only black https://i.imgur.com/dStJ1Og.png
//2px only black https://i.imgur.com/5z46WVp.png
//88x62px only black https://i.imgur.com/ZtGMUh9.png
//88x62px black and red https://i.imgur.com/67IZCaD.png
//220x297px black and red https://i.imgur.com/KTNnJGF.jpg
//3000x4000px black with red dot(1px) https://i.imgur.com/JiHtQuR.jpg

getPixels("https://i.imgur.com/JiHtQuR.jpg", function(err, ndarray) {
    if(err) {
        console.log("Bad image path!");
        return;
    }

    const firstPixel = [ndarray.data[0], ndarray.data[1], ndarray.data[2], ndarray.data[3]];
    const dummyArray = new Uint8Array(Array(ndarray.data.length / 4).fill(firstPixel).flat());
    const originalArrString = JSON.stringify(ndarray.data);
    const dummyArrString = JSON.stringify(dummyArray);

    if(originalArrString === dummyArrString) {
        console.log('image is in one color')
    } else {
        console.log('image is NOT in one color')
    }
});